Flash photography system

ABSTRACT

A flash photography system which comprises a photographic camera and an electronic flash device; 
     said photographic camera comprising 
     aperture value output means for producing aperture value under the flash light photographing, 
     flash light stop signal output means for integrating output value of a light value of a photographing object and for producing a signal for stopping emission of a flash light when the integrated value reaches a predetermined value, 
     said flash device comprising 
     calculating means for calculating a maximum photographing distance which is covered by the flash light for effecting a correct exposure on the photographing object on the basis of a maximum light value of the flash light and the aperture value fed from the aperture value output means, and 
     display means for displaying the maximum photographing distance on the basis of the output of the calculating means.

This application is a divisional application of application Ser. No.132,910, filed Dec. 11, 1987 now U.S. Pat. No. 4,839,687, which is acontinuation of application Ser. No. 801,303, filed Nov. 25, 1985 and isnow U.S. Pat. No. 4,755,845, which is a division of application Ser. No.554,870, filed Oct. 24, 1983, and is now U.S. Pat. No. 4,558,939.

FIELD OF THE INVENTION

The present invention relates to a flash light photography system, andmore particularly to a photographing system having a display means fordisplaying photographing distance or distance range which is covered bylight of a flash device for effecting a correct exposure of thephotographic object to be photographed.

BACKGROUND QF THE INVENTION

In a TTL automatic flash (through-the-lens light measurement type flashlight control) photographing system in which a flash light emission isstopped by a flash stop signal produced by a photographic camera whenthe value of the integrated amount of the light emitted from the flashdevice, reflected by the photographic object, and in turn having passedthrough the diaphragm aperture of the camera, reaches a predeterminedvalue; a maximum camera-to-object distance range which can be covered bythe maximum light quantity of the flash device for effecting a correctexposure on the photographic object (referred to as the flash-availabledistance range) is varied depending on the actual diaphragm aperturesize for the camera exposure operation. (see, for example U.S. Pat. No.4,359,275)

Conventional TTL automatic flash photography systems can not indicatesuch flash-available distance range since the conventional flash devicesare not provided with means for receiving data of the actual diaphragmaperture size of the camera.

There are other known types of flash light photography systems in whichthe light from the photographic object is measured by light measuringmeans provided in the flash device and the flash light is stopped whenthe integrated value of the output of the light measuring means reachesa predetermined value, while the maximum light quantity data of theflash device is transferred to the camera. (see, for example JapanesePatent Application laid-open No. 54-158923) In this type of flash lightphotographing system, the maximum flash-available photographing distanceis calculated by the maximum light quantity and the diaphragm aperturevalue calculated or manually set and transferred to display means fordisplaying the maximum photographing distance in the view finder of thecamera

This type of flash light photographing system has such drawbacks asfollows:

(a) the size of the characters for the distances displayed in the viewfinder is too small to read;

(b) in order to read the flash-available distance range on the flashdevice, the operator must adjust a calculating plate to a positioncorresponding to the diaphragm aperture value set in the camera then hemust read the flash-available distance range; and

(c) since only the maximum photographing distance is displayed, theoperator can not read the the minimum photographing distance of theflash-available distance range.

Other known flash devices are provided with display means for displayingthe falsh available distance range in accordance with the calculation ofthe maximum photographing distance on the bases of a manually setaperture value and the maximum light value of the flash device. (see,for example, Japanese laid-open Patent Application No. 57-66429) In theflash device of this type, the diaphragm aperture value must be set bothin the camera and the flash device. Therefore the setting of thediaphragm aperture value in the flash device may be overlooked.

SUMMARY OF THE INVENTION

An essential object of the present invention is to provide a flashphotography system having a display means for displaying theflash-available distance range without requiring a specific operationtherefor.

Another object of the present invention is to provide a flash devicehaving display means for displaying the maximum distance range and theflash-available distance range which can be read by operators withoutdifficulty.

A still further object of the present invention is to provide a flashdevice having terminals which can be connected with the correspondingterminals of the camera such that the various data can be transferredthrough the terminals.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing one embodiment of the flash lightphotographing system according to the present invention,

FIG. 2 is a schematic diagram showing an example of the displayaccording to the present invention,

FIG. 3 is a circuit diagram showing a modification of part of thecircuit shown in FIG. 1,

FIG. 4 is a circuit diagram showing a still further embodiment of thepresent invention,

FIGS. 5 and 6 are schematic diagrams showing the lens arrangement of acamera used in the present invention,

FIGS. 7a, 7b and 7care flow charts showing the operation of thephotographing system shown in FIG. 4,

FIGS. 8 through 10 are characteristic curves showing the operation ofthe photographing system shown in FIG. 4,

FIGS. 11a, 11b, 11c, 12a and 12b are flow charts showing the operationof the photographing system shown in FIG. 4,

FIGS. 13a and 13b show a detailed circuit diagram of a flash controlcircuit in FIG. 4,

FIGS. 14a and 14b show a detailed circuit diagram of a flash deviceshown in FIG. 4,

FIG. 15 is a block diagram showing one example of a display used in theembodiment of FIG. 4,

FIG. 16 is a flow chart showing a modification of the flow chart shownin FIG. 11, and

FIGS. 17a, 17b and 17c show a detailed circuit diagram of a lens circuitand an interface circuit used in the embodiment shown in FIG. 4.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIG. 1, a flash control device FC is provided in a camera,wherein a film sensitivity setting unit SS produces film sensitivitydata Sv manually set by a film sensitivity setting member (not shown).An arithmetic unit ALU1 produces a diaphragm aperture value Avf for thecorrect exposure determined by the brightness of the photographic objectand the film sensitivity.

An aperture size control unit CA controls the actual size of thediaphragm aperture APL of the camera in accordance with the aperturevalue Avf.

A flash device FL comprises a mechanism for controlling the lightdistribution characteristics by changing the relative position between alight emission panel and a reflection panel provided in the flash devicein a known manner. A circuit GS produces a signal representing therelative position between the light emission panel and the reflectionpanel. A circuit PS produces an output signal designating whether anormal light emission panel or wide light emission panel is used.

A light amount setting circuit MDO produces signals representing thevalues of the maximum light amount Ivmax and minimum light amount Ivminobtainable from the flash device FL.

The output data of the light amount setting circuit MDO is transferredto a read unit REAl provided in the camera through the terminals JF2 andJB6 connected with each other when the flash device is attached to thecamera. The data read in the read unit REAl is transferred to anarithmetic unit ALU2, which calculates

    Ivmax+Sv-Avf=Dmax.

The data Dvmax shows the maximum photographing distance that can providea correct or proper exposure by the camera with the flash device beingused and the actual diaphragm aperture being set at Avf.

A data selector SELl outputs a signal representing the maximumphotographing distance Dvmax when either the X contact or camera synchroswitch SX is opened and a flash stop signal is input from a circuit FTTwhen the X contact SX is closed. The output of the data selector SELl istransferred to the flash device FL through the terminals JB5 and JF1.The signal of the X contact SX operation is also transferred to the dataselector SEL2. The data selector SEL2 transfers the signal of themaximum photographing distance Dvmax fed from the terminal FJ1 to theread unit REA2 when the X contact SX is opened. On the other hand, thedata selector SEL2 transfers the flash stop signal from the terminal JF1to the flash light control circuit FLC when the X contact SX is closed.

The signal of the maximum photographing distance Dvmax is input to adisplay unit DPRl to indicate the maximum photographing distance Dvmaxin digital form. A change over switch DS selects the unit of thedistance specifically to be displayed by the display unit DPRl. With theswitch DS connected with the m terminal, the display unit displays thedistance in terms of metric units and with the switch DS connected withthe ft terminal, the display device displays the distance in terms ofthe foot-pound unit.

The data of the maximum photographing distance Dvmax stored in the readunit REA 2 is supplied to a subtractor SUB, which calculates the minimumphotographing distance Dvmin by the following equation.

    Dvmax-Dvd=Dvmin.

The data Dvd is fed from a circuit FXD1 and has a constant valuedetermined as a function of the ratio of the minimum light value and themaximum light value of the flash device. In the preferred embodiment,the apex value Dvmin of the minimum photographing distance can beobtained by subtracting the constant Dvd from the apex value Dvmax ofthe maximum photographing distance. This calculation is necessary due tothe fact that the ratio of the minimum light value and the maximum lightvalue does change with the light distribution characteristic of theflash device. The output of the subtractor SUB is applied to acomparator CMP. A circuit FXD2 produces an apex value Dvc of the minimumphotographing distance determined by parallax representing the distancebetween the optical axis of the light emitted from the flash tube suchas a Xenon tube and the optical axis of the photographic lens of thecamera. The value Dvc is -1 for 0.7 m for example. The data of the valueDvc is supplied to the comparator CMP, which compares the minimumphotographing distance Dvmin with the value Dvc to output a "High"signal if Dvmin>Dvc and a "Low" signal if Dvmin<Dvc. A data selectorSEL3 outputs a signal representing the value Dvmin upon receipt of the"High" signal from the comparator CMP and a signal representing thevalue Dvc upon receipt of the "Low" signal from the comparator CMP.These values are displayed by the display unit DPRI as shown in FIG. 2in which the area (A) displays the actual photographing distance, area(B) displays the maximum photographing distance and the area (C)displays the minimum photographing distance. The flash-availabledistance is displayed by the display areas (B) and (C) and the area (D)dislays the F number.

Referring to FIG. 1 again, when the X contact SX is closed, a Xenon tubeXE emits the flash light, with an integrating circuit in the circuit FTTintegrating the output of a photo sensor (not shown) which receives andmeasures in a known manner the flash light reflected from a photographicobject. Simultaneously, the data selector SEL2 becomes ready to producethe flash stop signal through the terminal JF1 to the flash lightcontrol circuit FLC. When the output of the integrating circuit reachesa predeterined value, the circuit FTT outputs the flash stop signal tothe flash light control circuit FLC to stop the flash light emission bythe Xenon tube.

Referring to FIG. 3 showing another embodiment of the photographingsystem according to the present invention, wherein the arithmetic unitALU2 for calculating the maximum photographing distance Dvmax isprovided in the flash device FL. Also a circuit SS1 for producing thefilm sensitivity is provided in the flash device FL. The arithmetic unitALU2 calculates the equation:

    Ivmax+Sv-Avf=Dvmax

in a similar manner as previously described with reference to theembodiment shown in FIG. 1 on the basis of the value Ivmax applied fromthe circuit MDO, the aperture value Avf from the read unit REA2 and thefilm sensitivity Sv from the circuit SS1.

In FIG. 4, a central processing unit 1 (referred to as CPU hereinafter)such as a microprocessor is provided for controlling the various controlsequences of the circuit arrangement shown in FIG. 5. Battery BBprovides power to the camera and power ON reset circuit POI produces apower ON reset signal PR1, which is sent to the reset input terminal REof the CPU 1 for initialization of the CPU 1. An oscillator OSC producesa clock pulse train CP which is supplied to the CPU 1 and the essentialparts of the circuits for controlling them in synchronism with the clockpulse.

A display device DP1 made of a liquid crystal display having eightsegments for each digit receives the signals fed from the terminals SEGand common terminal COM of the CPU 1 for displaying the exposure controlvalues and various exposure control modes used in the camera system. Thebattery BB supplies the DC power to the CPU 1, the oscillator OSC, thedisplay device DPl, an interface circuit IF, a flash control device FC,a data selector MP1, inverters IN1 through IN6, and an AND gate AN1through a line +E.

When a light measurement switch MS is closed to be ON for a lightmeasurement operation, a "High" level signal is applied to the inputterminal ST of the CPU 1 to start reading the data for the exposurecontrol. Simultaneously, analog-to-digital conversion of the result ofthe light measurement and the calculation of the exposure value anddisplay are started. Also when the light measurement switch MS isclosed, a transistor BT1 conducts so that the DC power is supplied tothe circuit arrangement through the line +VB. When the DC power issupplied from the line +VB, a power ON reset circuit PO2 generates apower ON reset signal PR2, which is supplied to an exposure time controlcircuit CT and the aperture control circuit CA to reset them.

An exposure control unit 3 (indicated by a dotted line) is composed ofthe exposure time control circuit CT, the aperture control circuit CAand a pulse generator PG. The exposure time control circuit CT receivesthe exposure time data Tv from the output terminal OP1 of the CPU 1 toproduce a time interval signal representing a time interval 2^(-Tv)between the beginning of shutter release and ending of shutter closureon the basis of the clock pulses CP. The exposure time can be controlledby the time interval signal.

The pulse generator PG generates a pulse train the number of pulses ofwhich corresponds to the amount of rotation angle of an aperture ring(not shown) provided in the lens LE. The aperture control circuit CA issupplied with the data Av representing a number of steps of thedecreasing value of the aperture fed from the output terminal OP2 of theCPU 1 and the pulse train from the pulse generator PG.

Aperture control circuit CA counts the number of pulses fed from thepulse generator PG and compares the number of pulses thus counted andthe data Av representing the calculated aperture value fed from the CPU1 to produce an output signal when the counted number of the pulsescoincides with the data Av for stopping rotation of the aperture ring.

A switch LS is provided for detecting the lens LE attached to thecamera. The switch LS is closed upon mounting of the lens to the cameraand opened upon removal of the lens from the camera. When the switch LSis closed a high signal is supplied to the input terminal i1 of the CPU1 through the inverter IN1 to cause the CPU 1 to read-in the data of thelens LE to calculate the exposure time. When the switch LS is opened,the input terminal i1 of the CPU 1 is low so that the CPU 1 performsother calculations as hereinafter described.

A block 5 shows an exposure data output unit, wherein PD1 is a photosensor mounted in the camera as shown in FIGS. 13 and 14. In FIG. 5, anaperture control device APL is opened and a reflection mirror RM is inthe dropped position so as to introduce light rays from the photographicobject to the finder optical system. The rays of light of thephotographic object passes a half mirror disposed in the central portionof the reflection mirror RM, and is reflected by a relfection plane RL,and subsequently enters the photo sensor PD1 through a condenser lensLEB. In such a state, the operational amplifier OA1 in FIG. 4 generatesa light measurement output Bv+Sv-Avo, wherein Bv is the brightness ofthe photographing object, Avo is an open aperture value, and Sv is anapex value corresponding to the film sensitivity.

In FIG. 6, the diaphragm aperture APL is opened to a value correspondingto the calculated or set aperture value Av, while the reflection mirrorRM and the reflection plane RL are raised to allow passage of the lightrays of the photographic object. The shutter SHT is in a releasedposition, so that the rays of light having passed the lens LE and thediaphragm aperture APL are reflected by the photographic film FIL and inturn, the rays of light of the object enter the photo sensor PD1. Insuch a state, the operational amplifier OA1 generates an output ofBv+Sv-Av. As hereinafter described the amount of light of the flashdevice FL is controlled by the output of the operation amplifier OA1.

The analog-to-digital converter (referred to as AD converterhereinafter) Ad operates to convert the light measurement data Bv+Sv-Avoin analog form fed from the operational amplifier OA1 into a digitalform when the CPU 1 produces a "High" level output pulse from the outputterminal 06. The digital data is fed to the input terminal IP2 of a dataselector MP1.

An aperture setting circuit AS supplies data Avs-Avo representing theposition of the aperture control ring of the interchangeable lens LE tothe input terminal IP3 of the data selector MP1.

An exposure time setting circuit TS generates exposure time data whichcorresponds to the exposure time manually set by an exposure timesetting member provided in the camera. The output terminal of theexposure time setting circuit TS is connected with the input terminalIP4 of the data selector MP1.

A film sensitivity setting circuit SS generates digital datacorresponding to the film sensitivity manually set by a film sensitivitysetting member (not shown) provided in the camera. The output terminalof the film sensitivity setting circuit SS is connected with the inputterminal IP5 of the data selector MP1.

A mode setting circuit MSO generates signals representing one of theexposure control modes which is set by a mode setting member provided inthe camera. The output terminal of the mode setting circuit MSO isconnected with the input terminal IP5 of the data selector MP1.

An interface IF reads various data from the interchangeable lens circuitLEC when the output terminal 05 of the CPU 1 becomes "High". Aftercompletion of the read-in operation, the interface IF transfer thevarious data to the CPU 1 through the data selector MP1 and an externaldata bus DB corresponding to the control data of 4 bits fed from theoutput terminal OP3 of the CPU 1. A detailed circuit arrangement of theinterface IF will be explained with reference to FIG. 17 later.

A flash light control circuit FC transfer various data between the CPU 1and the flash device FL in response to the signals fed from the outputterminals 05, 08, 09, 010 and 011 of the CPU 1 and the inverter IN2. Adetailed circuit arrangement of the flash light control device FC willbe described later.

The data selector MP1 transfers the output data on the input terminalsIP1 through IP7 to the CPU 1 through the data bus DB in response to 4bits of data applied to the selection terminal SL from the outputtermial OP3 of the CPU 1.

Table 2 shows which kinds of data can be transferred to the data bus DBthrough the data selector MP1 in response to the input data on theselection terminal SL. For example, when the selection terminal SL is"0000" or "0_(H) ", wherein the index H means hexa decimal digit, setexposure time data Tvs applied to the input terminal IP4 is transferredto the data bus DB from the data selector MP1.

When the selection termial SL is one of the data of 6_(H) through C_(H),the interface IF produces the data which are read from the lens circuitLEC as shown in the Table 4, the data is fed to the input terminal IP1of the data selector MP1 and in turn transferred to the data bus DB toinput the data in the CPU 1. When the lens detection switch LS isopened, i.e., an interchangeable lens is not attached to the camera, theinput terminal il of the CPU is kept "Low" so that the CPU 1 producesonly the data of "0_(H) " through "4_(H) ", therefore the various datarepresenting the lens LE can not be supplied to the CPU 1.

A release switch RS is closed upon depression of the release button orshutter button of the camera and opened upon releasing of the hand fromthe release button.

A switch CS is operated to close upon completion of the film winding andto open so as to prevent undesired exposure.

The signal of the operation of release switch RS is applied to one inputterminal of the AND gate AN1 through the inverter IN4. On the otherhand, the signal of the operation of switch CS is applied to the otherinput terminal of the AND gate AN1 through the inverter IN5 and to theinput terminal i2 of the CPU 1. The output terminal of the AND gate AN1is connected with the interrupt terminal it of the CPU 1.

The output terminal 05 of the CPU 1 is connected with an input terminalof the inverter IN3, the output of which is connected with the base ofthe transistor BT1, through a resistor so that the transistor BT1 ismaintained in the ON state even if the light measurement switch MS isopened during an exposure control operation. The output terminal 06 ofthe CPU 1 is "High" while the interface IF reads in the data of the lensLE. The output terminal 06 is connected with an input terminal of aninverter IN6, the output of which is connected with the base of thetransistor BT2 so that the transistor BT2 conducts to supply DC power tothe lens circuit LEC through the terminals JB1 and JL1 when the output06 is "High" and the output of the inverter IN6 is "Low". In the lenscircuit LEC, a ROM RO stores various data of the lens.

The address data and the stored data in the ROM RO are transferredbetween the lens circuit LEC and the interface IF through the connectionterminals JB3 and JL3 in synchronism with the clock pulse train CPLwhich is supplied to the lens circuit LEC from the IF through theconnection terminals JB2 and JL2.

The operation of the circuit arrangement of the camera system shown inFIG. 4 is explained hereinafter with reference to FIG. 7.

When the camera system is not used, the CPU 1 is in a stand-by state andthe clock pulse train CP is not supplied to the CPU 1 so as to save theDC power supply of the battery BB. When the light measurement switch MSis closed a "High" signal is fed to the CPU 1 to start it. The flashcontrol circuit FC produces a start signal for starting a voltagebooster in the flash device FL. At the step #1, the state of theterminal ST is determined. If the state of the terminal ST is "High",the program goes to step #7 to reset a register TR functioning as atimer. In the step #8, whether or not the lens LE is attached to thecamera is detected by the state of the input terminal i1 If the inputterminal il is "Low", the program goes to step #10. However, if theterminal i1 is "High", the program goes to step #9, causing the outputterminal 06 to be "High", thereby causing the transistor BT2 to beconductive to supply the DC power to the lens circuit LEC, and causingthe interface IF to start to read out the data of the lens LE attachedto the camera. Then the program advances to step #10, wherein the outputterminal 09 of the CPU 1 is "High" to cause the flash control circuitFLC to read out the data of the flash device FL1. Then the Program goesto step #11 to generate a "High" pulse from the output terminal 07 ofthe CPU 1. With the "High" pulse on the terminal 07, the A-D converterAD starts to convert the analog information of the light measurementresult fed from the operational amplifier OA1 to digital information. Inthe step #12, 4 bit data 0_(H) is set in the data register DR and the 4bit data 0_(H) appears on the output terminal OP3 of the CPU 1. With the0_(H) data, the exposure time data Tvs is output from the data selectorMP1. The data Tvs is stored in the register DR in the CPU 1. In the step#15, 1 is added to the content of the register DR. Subsequently, in thestep #16, whether or not the data of the register is 5_(H) isdetermined. If the content of the register DR is not 5_(H), the programreturns to step #13 and repeats the sequence described above.

When the content of the register DR is 1_(H), the film sensitivity Sv isread in the CPU 1. When the content of the register DR is 2_(H), theexposure mode data is read in the CPU 1.

When the content of the register DR is 3_(H), the AD conversion in theAD converter AD is completed to generate data of the brightness of themain object, and

    Bv+Sv-Avo

is read into the CPU 1 to store it in a suitable register.

In a similar manner as described above, when the contents of the dataregister DR becomes "4_(H) ", the data selector MP1 transfers the flashcontrol data on the input terminal IP7 fed from the flash device FL tothe CPU 1. In the step #16, as the content of the data register DR is"5_(H) ", the program goes to step #17, whereby the output 09 becomes"Low" to disable the flash control device FC and in turn the programflow goes to step #18, wherein the state of the input terminal i1 isdetermined. In a case where the switch LS is open, i.e., the output ofthe inverter IN1 is "Low", the program flow goes to step #29 the detailof which will be described later. In a case where the interchangeablelens LE is attached to the camera with the switch LS closed, i.e., theinput terminal il is "High", the program flow goes to step #19. In thestep #19, the data 5_(H) in the register DR is output on the terminalOP3 so that the data representing the aperture value Avs-Avo istransferred to the data bus DB for applying the data to the CPU 1. Inthe step #20, the data AVS-Avo is stored in a register (not shown) andthereafter, "1" is added to the content of the data register DB and theprogram flow goes to step #22.

In the step #22, the CPU 1 waits for the time when the input terminal i3becomes "High". When the read-in operation of the data of the lenscircuit LEC in the interface IF is completed, the interface IF applies a"High" signal to the input terminal i3 of the CPU 1.

With the "High" signal of the interface IF, the program flow goes tostep #23, wherein the output terminal 06 of the CPU becomes "Low" whichis reversed to "High" by the inverter IN6, thereby causing thetransistor BT2 to be non-conductive, resulting in cutting off the DCpower supply to the lens circuit LES.

When the input terminal i3 of the CPU 1 becomes "High", certain of thedata stored in the interface IF is selectively transferred to the CPU 1depending on the contents of the data on the terminal OP3 of the CPU 1.Namely, checking data is transferred to the input terminal IP1 of thedata selector MP1 corresponding to the data 6_(H), similarly the openaperture value Avo for the data 7_(H), the maximum aperture value Avmfor the data 8_(H), the minimum focal distance fw for 9_(H), the maximumfocal distance ft for A_(H), Dv (explained hereinafter) for B_(H), theset picture taking distance Dv for C_(H) and the set focal distance fsfor D_(H) are respectively transferred to the input terminal IP1 of thedata selector MP1. These data are transferred to the CPU 1. When theread-in operation of the data in the CPU 1 is completed in the step #27,the content E_(H) of the data register DB is detected to advance theprogram flow to the step # 28. In the step #28, whether or not thechecking date is applied to the CPU 1 is determined. The checking datashows that the interchangeable lens is attached to the camera. Thechecking data is the same for all kinds of interchangeable lenses.

When the checking data is detected, the program flow goes to the step#35. However, when the checking data is not detected, the program flowgoes to the step #29. The latter case occurs either when any one of theinterchangeable lenses is attached to the camera or when an accessorysuch as an intermediate ring or a bellows is interposed between the lensand the camera.

In a case where the step #29 is selected, whether or not the flash lightphotographing mode signal is present is determined in the step #29 fordetermining whether or not the flash device FL is attached to thecamera. When the flash device FL is not attached to the camera, all thedata o the connecting terminal JB6 is made "Low", then the program flowgoes to the step #31 so as to calculate data for ambient lightphotographing. When one of the aperture priority exposure mode orexposure priority aperture mode is selected by a mode selecting device,the light measurement circuit ME produces Bv -Avn, wherein Avn is theeffective aperture value. Then the exposure time Tvc is calculated bythe equation

    (Bv-Avn)+Sv=Tvc.

The speed of the shutter SHT of the camera is controlled by the valuecalculated by the above equation. In this case, the decreasing value Avof the aperture is zero and therefore the diaphragm aperture APL is notdrawn. In this case the exposure time is controlled by the TTL (throughthe lens) exposure measurement by the aperture setting method.

If the manual exposure control mode is selected, the exposure time iscontrolled by the manually set value, the decreasing value of theaperture is set to zero so that the size of the actual diaphragmaperture APL is kept unchanged. However, when the fact that the flashdevice is attached to the camera is detected in the step #29, theprogram flow goes to step #30 for calculating the control data for thephotographing. In this case the aperture value Avf is made zero. Theexposure time value Tvf if set bY the exposure value corresponding tothe critical synchronizing exposure time such as 1/250 sec when one ofthe automatic exposure control mode is selected. In a case where themanual exposure control mode is selected, if the set exposure time Tvsis shorter than the critical synchronizing exposure time, the data Tvfis selected for the exposure time control. If the set exposure time Tvsis longer than the critical synchronizing exposure time, the setexposure time Tvs is selected as the exposure time data Tvf for theflash control.

Subsequently, the calculation for the exposure data for thepicture-taking with ambient light is performed in the step #31 asdescribed above, and then the program flow goes to the step #32, whereinwhether or not the main capacitor in the flash device Fl is charged tothe predetermined voltage is determined by the data sent from the flashdevice to the CPU 1. When the charged voltage reaches the predeterminedvalue, the program flow goes to the step #33, whereby a display deviceis lit to show that flash picture-taking is ready. If the voltage in themain capacitor does not reach the predetermined value, the program flowgoes to the step #34 to display that the picture-taking with ambientlight is ready.

In the step #28 described above, when the checking data is detected, theprogram flow goes to the step #35, wherein upon detecting that the flashdevice FL is attached to the camera, the calculation of the data for theflash light photograhing is made, and in turn the program flow goes tothe step #37. On the other hand, upon detecting that the flash device isnot attached to the camera, the program flow goes to the step #37 forcalculation of the following equation for photographing with ambientlight.

    (Bv+Sv-Avo)-Avo=Ev                                         (1).

In addition when the program mode is set, the following equation

    p·Ev=Av(o<p<1)                                    (2)

is calculation. When Avo≦Avc≦Avm, (wherein Avo is the open aperturevalue and Avm is the maximum aperture value), the following equation

    Ev-Av=Tv                                                   (3)

is calculated. The calculated value Tv is used as the exposure timevalue for the picture taking with ambient light. When Av<Avo, thefollowing equation

    Ev-Avo=Tv                                                  (4)

is calculated. In a case where the calculated exposure time Tv issmaller than Tv_(min), the value Tv_(min), which is the maximum exposuretime, is used as the control value Tvc with a warning lamp lit forindicating that the exposure value thus calculated is under the desiredexposure value. When Tv≧Tv_(min) the value calculated by the equation(4) is used as the control value Tvc. Further, if the aperture value Avcalculated by the equation (2) is greater than Avm, the data Avm is usedas a control value and the following equation

    Ev-Avm=Tv                                                  (5)

is calculated, and if Tv is greater than Tv_(max) (Tv_(max) is theshortest exposure time) the value Tv_(max) is used as the control valueTvc with the warning lamp lit to indicate an overexposure.

In the aperture priority exposure mode (referred to as A modehereinafter), the set aperture value Avs is calculated by the followingequation

    (Avs-Avo)+Avo=Avs                                          (6).

Subsequently the exposure time is calculated by the equation

    Ev-Avs=Tv                                                  (7).

When Tv_(min) ≦Tv≦Tv_(max), the calculated exposure time Tv and the setaperture value Avs are used as the control data Avc and Tvc. WhenTv<Tv_(min) the data Tv_(min) is used as the control data Tvc and thefollowing question

    Ev-Tv.sub.min =Av                                          (8)

is calculated. When Av≧Av_(min), the calculated aperture value Av isused as the control data. When Av<Av_(min), the data Av_(min) is used asa control data Avc with the warning lamp lit to indicate anunderexposure.

When the calculated exposure time Tv is greater than the shortestexposure time TV_(max), the shortest exposure time Tv_(max) is used as acontrol data and the following equation is calculated

    Ev-Tv.sub.max =Av                                          (9).

When Av<Avm, the data Avm is used as a control data Avc with the warninglamp lit to indicate an overexposure. However, when Av≧Avm, the data ofthe aperture value Av calculated by the equation (9) is used as thecontrol data Avc for the aperture value.

In the exposure time priority aperture control mode (referred to as Smode),

    Ev-Tvs=Av                                                  (10)

is calculated. When Avo≦Av≦Avm, the set exposure time Tvs and theaperture value Av calculated by the equation (10) are used as thecontrol data Avc and Tvc. When Av≦Avo, the data Avo is used as thecontrol data Avc and the following equation is calculated

    Ev-Avo=Tv                                                  (11).

When≧Tv_(min), the exposure time Tv calculated by the equation (11) isused as the control data Tvc. When Tv<Tv_(min), the value Tv_(min) isused as the control data Tvc with the warning lamp lit to indicate anunderexposure. When the data Av calculated by the equation (10) isgreater than Avm, the value Avm is used as the control data and thefollowing equation is calculated

    Ev-Avm (=Avc)=Tv                                           (12)

When Tv calculated by the equation (12) is greater than Tv_(max), thevalue Tv_(max) is used as the control data with the warning lamp lit toindicate an overexposure. When the value Tv is smaller than Tv_(max),the data Tv calculated by the equation (12) is used as the control dataTvc.

In the manual setting mode (referred to as M mode), the set aperturevalue Avs and the set exposure time value Tvs are used as the controldata Avs and Tvs, and the following equation is calculated

    Ev-(Avc+Tvc)=ΔEv                                     (13).

After the calculation as described above according to any one of the setmodes is completed in the step #37, the program flow goes to the step#38.

The following description is made to explain the contents of the step#36 which is performed when the flash device FL is attached to thecamera.

Referring to FIG. 11, in the step #101, the following equation iscalculated.

    (Bv-Avo)+Sv+Avo=Ev                                         (15)

Subsequent to the calculation, which of the TTL -mode or the externallight mode is selected by the flash device FL is determined in the step#102. If the TTL mode is selected, the program flow goes to the step#103. If the external light mode is selected, the program flow goes tothe step #201 shown FIG. 12.

In case of the TTL mode, if the camera is set in the P mode, the programflow goes to #104, and if not the P mode, the step #150 is selected. Ina case where the TTL mode and P mode are selected, the CPU determineswhether or not the focal distance of the interchangeable lens LEattached to the camera is shorter than 30 mm in the step #104. In caseof YES, an aperture value 6 (F8) is set as the data Avf₅ as shown in W1in FIG. 9 for the film sensitivity Sv=5 in the step #105, and in turnthe exposure time data 5 (1/30 sec) is set as the synchronized exposuretime Tvf in the step #106. When the focal distance of theinterchangeable lens is longer than 30 mm, whether or not the focaldistance is in the range of 31 mm to 55 mm is determined in the step#107. In case of YES, the aperture value Avfs is set by 5 (F5.6) (F5.6)and the exposure time Tvf is set by 6 (1/60 sec) as shown by W2 in FIG.9. In a case where the focal distance is larger than 55 mm, whether ornot the focal distance is in the range of 56 mm to 120 mm is determinedin the step #110. In case of YES the aperture value Avf₅ is set by 4(F4) and the exposure time Tvf₅ is set by 7 (1/125 sec) as shown by T1in FIG. 8. In case of NO, the aperture value Avf₅ is set by 3 (F2.3) andthe exposure time Tvf is set by 8 (1/250 sec) in the step #113, then theprogram flow goes to the step #115.

In the step #115,

    Sv-5=ΔSv                                             (16)

is calculated and the program flow goes to the step #116 wherein

    Avf.sub.5 +ΔSv                                       (17)

is calculated. By determining the aperture value Avf as described above,since the incident light from the flash device FL to the camera can bedecreased so that the aperture value can be decreased as small aspossible in such a state that the flash available operation rangebetween the camera and the flash device is kept constant. Accordingly,in photographing with the flash light, the depth of the focus can be asdeep as possible. In case where the film sensitivity is different fromSv=5 by ΔSv, the aperture value can be decreased according to the valueΔSv, and the flash available operation range between the flash deviceand the camera is kept unchanged.

In the step #117, the CPU 1 determines whether or not the aperture valueAvf obtained by the equation (17) is smaller than Avo and when Avf<Avo,the value Avo is used as the aperture value Avf for photographing withthe flash device FL in the step #118. When Avo≦Avf, the CPU 1 determinesif Avm<Avf in the step #119. When Avm<Avf, Avm is used as Avf and whenAvm≧Avf the value Avf calculated by the equation (17) is used as theaperture value and then the program flow goes to the step #121.

In the step #121, the CPU 1 determines if the following equation

    Avf+Tvf≧Ev+1                                        (18)

is satisfied, and if YES, the program flow goes to step #131, on theother hand, if NO, the program flow goes to step #122. The Ev valuecorresponding to the change over point of the judgment at the step #121is Ev=10. Accordingly, if the Ev is smaller than 10, the data Tvf andAvf are used without modification in the step #131. On the other hand,if the value Ev is equal to or greater than 10, the data Tvf and Avf aremodified as hereinafter described and the program flow goes to the step#132.

In the step #122,

    Ev+1-Avf=Tva                                               (19)

is calculated and in the step #123, if Tva is greater than 8 isdetermined. When Tva is equal to or small than 8, the value Tva obtainedby the equation (19) is used as the exposure time control data Tvf andthe program flow goes to the step #131.

The operation performed in the steps #121 and #122 shows that in a casewhere the focal distance is greater than 30 mm the aperture value isforcibly set by the data W1 for the exposure value Ev within the rangeof 10≦Ev≦13. Similarly, in a case where the focal distance of the lensis in the range of 31 mm to 55 mm, the aperture value is forcibly set bythe data W2 for the brightness Ev within the range of 10≦Ev≦12. The dataT1 corresponds to the brightness Ev in the range

    10=Ev≦11. If Tva<8, Ev+1-Tvf=Ava                    (20)

is calculated by putting Tvf=8. Subsequently, if Ava≦ Avm, the aperturevalue Ava calculated by the equation (20) is used as the control data,and in turn the program flow goes to the step #131. If Ava>Avm, the dataAvm is used as the control data with the warning lamp (display device OEin FIG. 4) lit to indicate an overexposure and the program flow goes tothe step #131. The steps from #124 to #129 show the operation fordetermining the data of the aperture value and the exposure timerelative to the brightness Ev in FIG. 8, i.e., the aperture value can becalculated along the slanting line L₀ for Ev≧13 when the data W1 isselected, for Ev≧12 when the data W2 is selected, for Ev≧11 when thedata T1 is selected and for Ev≧10 when the data T2 is selected.

In the above description, the aperture value Tva and the exposure timeTva are calculated on the basis of the data Ev+1, namely the constant k2is designated as 1Ev, however, the constant k2 can be selected by adesired value ranging from 0Ev to 2Ev.

The-calculation of the exposure data for the S mode will be describedhereinafter.

FIG. 9 shows the relationships between Av, Tv and Ev taking Tvs as aparameter wherein the real lines correspond to the parameter Tvs=3 (1/8sec), the dotted lines correspond to Tvs=6 (1/60 sec) and the chainlines correspond to Tvs=8 (1/250 sec).

In FIG. 11 if the mode is not the P mode, the program flow goes to thestep #150 to determine if the mode is the S mode. In case of the S mode,the CPU 1 determines whether or not Tvs is equal to or less than 8 inthe step #151. If Tvs ≦8, the set exposure time Tvs is set as thecontrol value for the exposure time Tvf and the program flow goes to thestep #154. However, if Tvs>8, a value 8 is set for Tvf in the step #153and the program flow goes to the step #154, wherein

    Ev+1-Tvf=Ava                                               (21)

is calculated to obtain the aperture control value Ava. In the step#155, if Ava<Avo is detected the program flow goes to step #156.

In the step #156, the data Avo is used for the aperture control data Avfand the warning lamp UE is lit to indicate the underexposure, then theprogram flow goes to the step #131. It is noted that the operation ofthe step #156 corresponds to the range Ev<3 when the characteristiccurve is represented by the real line, to the range Ev<6 for thecharacteristic curve of the dotted line and to the range Ev<8 for thechain line.

If Ava≧Avo is determined in the step #155, the program flow goes to thestep #158, wherein if Ava>Avm is determined. If Ava≦Avm, the aperturevalue Ava calculated by the equation (21) is used as the aperturecontrol data, and then the program flow goes to the step #131. Thisoperation corresponds to the range 3≦Ev≦11 for the characteristic curveshown by the real line in FIG. 9, to the range 6≦Ev ≦14 for thecharacteristic curve shown by the dotted and to the range 8≦Ev≦16 forthe characteristic curve shown by the chain line.

If Ava>Avm is determined in the step #158, the value Avm is selected asthe aperture control data Avf in the step #159 and the followingequation

    Ev+1-Avf=Tva                                               (22)

is calculated in the step #160.

If Tva≦8 is determined in the step #161, the program flow goes to thestep #162, wherein the value Tva calculated in the equation (22) isselected as the exposure time control data Tvf and then the program flowgoes to the step #131. This operation corresponds to the range 11≦Ev≦16for the characteristic curve shown in the real line in FIG. 10 and tothe range 14≦Ev≦16 for the characteristic curve shown in the dotted linein FIG. 9. There is no such a range as described above for the chainline.

If Tva>8 is detected in the step #161, the program flow goes to the step#163, wherein the exposure time control data Tvf is set to (1/250) withwarning lamp OE lit to indicate an overexposure, then the program flowgoes to the step #131. This operation corresponds to the range Ev>16 forthe characteristic curves shown in FIG. 10.

The operation in the A mode will be hereinafter described with referenceto FIG. 12.

When it is determined that the mode presently set is not the S mode inthe step #150, the program flow goes to the step #170, to determinewhether or not the present mode is the A mode. When the A mode isdetected, the program flow goes to the step #171, wherein the CPU 1determines whether or not the focal length of the interchangeable lensis attached to the camera. If the result of the judgment is YES, theprogram flow goes to the step #172 to designate the exposure timecontrol data Tvf as 5 (1/30 sec).

If the result of the judgment is NO, the program flow goes to the step#173 to determine whether the focal length of the interchangeable lensattached to the camera is in the range of 31 mm to 55 mm. If the resultof the judgment is YES, the program flow goes to the step #174 todesignate the exposure time control data Tvf as 6 (1/60 sec). If theresult of the judgment in the step #173 is NO, the program goes to thestep #175 to determine whether the focal length of the interchangeablelens is in the range of 56 mm to 120 mm. If the result of the judgmentis YES, the program flow goes to the step #176 to designate the exposuretime control data Tvf as 7 (1/125 sec). If the focal length of theinterchangeable lens is greater than 120 mm, the program flow goes tothe step #177 to designate the exposure time control data Tvf as 8(1/250 sec).

After the operation described above is completed, the program flow goesto the step #178 to determine whether the exposure time control data Tvfsatisfies the following equation

    Avs+Tvf≧Ev+1                                        (23)

If the equation (23) is satisfied, the program flow goes to the step#179 to designate the set aperture value data Avs as the desiredaperture value data Avf and then the program flow goes to the step #131.

The operation in the steps #178 and #179 means that in the example shownin FIG. 10, if the focal length of the interchangeable lens is shorterthan 30 mm (this range is shown as W1 in FIG. 10) and the aperture valueis set to the value 6, the brightness value Ev equal to or smaller than9 may be suitable for the photographing. Similarly for the focal lengthrange W2 (31 mm≦focal length≦55 mm) and the aperture value 5 thebrightness value in the range Ev₌ 10 can be used, for T1 (56 mm≦focallength≦120 mm) and T2 (focal length>121 mm) Ev≦11 and ≦12 can be used.

In a case where the equation (23 ) is not satisfied, the program flowgoes to the step #180 to calculate the following equation

    Ev+1-Avs=Tva                                               (24)

Then whether the data Tva is greater than 8 is determined in the step#181. If the result of the judgment in the step #181 is NO, i.e., thevalue Ev is equal to or smaller than 8, the program flow goes to thestep #188 to designate the exposure time control data Tva calculated bythe equation (24) as the desired exposure time control data Tvf and theprogram flow goes to the step #131. The operation in the steps #181 and#188 is performed for the respective ranges of the brightness 9<Ev<12for the focal length W1, 10≦Ev≦12 for the focal length W2 and 11<Ev<12for the focal length T1. In this case there is no suitable brightnessrange for the focal length T2.

If Tva>8 is detected in the step #181, the program flow goes to the step#182, wherein the exposure time control data Tvf is designated as 8. Theprogram flow goes to the step #183 to calculate

    Ev+1-Tvf=Ava                                               (25).

In the step #184, if Ava>Avm is determined. If Ava<Avm, the value Ava isdesignated as the aperture value control data Avf and the program flowgoes to the step #131. This operation is performed in the range12≦Ev≦16. If Ava> Avm, the program flow goes to the step #185 todesignate the data Avm as the aperture value control data Avf with thewarning lamp OE lit in the step #186 to indicate an overexposure, thenthe program flow goes to the step #131.

If the result of the judgment in the step #170 is NO, i.e., the mode setin the camera is not the A mode, the program flow goes to the step #190for the M mode. In the step #190, whether the exposure time data Tvs setby a manual operation is equal to or smaller than 8 is determined. IfTvs>8, the exposure time data is set to 8 and if Tvs<8, the set exposuretime data Tvs is used as the exposure time control data Tvf and theaperture value Avs is used as the value Avf in the step #175, then theprogram flow goes to the step #131.

In the step #102 shown in FIG. 12, if the result of the judgment is NO,i.e., otherwise the TTL mode is detected, the program flow goes to thestep #201 shown in FIG. 13 under such a judgment that the ambient lightphotographing mode is set in the flash device FL.

In the step #201, whether the M mode is set in the camera is determined.If the M mode is detected, the program flow goes to the step #202 todetermine if the set exposure time data Tvs is larger than 8. If theresult of the judgment is YES, the desired exposure time control dataTvf is set to 8. If the result of the judgment is NO, i.e., the data Tvsis equal to or small than 8, the set exposure time data Tvs is used asthe exposure time control data Tvf.

Subsequently, in the step #205, the set aperture value Avs is used asthe aperture value control data Avf, then the program flow goes to thestep #131.

In the step #201, if the result of the judgment is NO, the program flowgoes to the step #206 for each of the P mode, A mode and S mode todetermine whether the focal length of the interchangeable lens issmaller than 30 mm. If the result of the judgment is YES, the exposuretime control data Tvf is set to 5 and the program flow goes to the step#213. If the focal length is greater than 30 mm, the program flow goesto the step #208 to determine whether the focal length is in the rangeW2 (from 31 mm to 55 mm). If the result of the judgment in the step #208is YES, the exposure tim control data Tvf is set to 6, then the programflow goes to the step #213. If the result of the judgment in the step#208 is NO, the program flow goes to the step #210 to determine whetherthe focal length of the interchangeable lens is in the range T1 (from 56mm to 120 mm). If the result of the judgment is YES, the exposure timecontrol data Tvf is set to 7 and the program flow goes to the step #213.If the result of the judgment in the step #210 is NO, i.e., the focallength of the interchangeable lens is greater than 120 mm, the exposuretime control data Tvf is set to 8 and the program flow goes to the step#213.

In the step #213, the aperture control data Avf is obtained by the datacoming from the flash device FL and whether the aperture value controldata Avf is smaller than the value Avo in the step #214. If the judgmentis YES, the value Avo is used as the aperture value control data Avf andthe program flow goes to the step #218.

If the result of the judgment in the step #214 is NO, i.e., the aperturevalue control data Avf is equal to or greater than Avo, whether Avf>Avmis determined in the step #216. If the result of the judgment in thisstep is YES, the value Avm is used as the aperture control value Avf andthe program flow goes to the step #218. If the result of the judgment inthe step #216 is NO, i.e., the aperture value control date Avf≦Avm, theprogram flow goes to the step #218 to calculate the following equation

    Ev+1-Avf=Tva                                               (26).

Subsequently, whether the value Tva>Tvf is determined. If Tvf<Tva, theprogram flow goes to the step #131.

If Tva>Tvf, the program flow goes to the step #220 to determine whetherthe value Tva is equal to or small than 8. If the result of the judgmentis NO, the program flow goes to the step #222 to designate the value 8for the exposure time control data Tvf, then the program flow goes tothe step #131.

If the result of the judgment in the step #220 is YES, i.e., Tva≦8, thevalue Tva calculated by the equation (26) is used as the exposure timecontrol data Tvf, then the program flow goes to the step #131.

As explained above, in a case where pictures are taken under theexternal light photographing mode, the aperture value for the aperturecontrol device APL is controlled by the aperture value set in the flashdevice FL.

In a case where the exposure time control value determined by thebrightness of the photographic object has a value in the range U0between the exposure time value determined corresonding to the focallength of the interchangeable lens LE and the critical synchronizingexPosure value, the value Tvf is used as the desired exposure timecontrol data. When the exposure time control value determined by thebrightness of the photographic object is out of the range U0, theexposure time control data Tvf is used. In the step #131, a criticalaperture value Avd for the operation coupled with the flash device iscalculated on the basis of the maximum light emission value Iv_(max),film sensitivity Sv and the distance Dv using the following equation

    Iv.sub.max +Sv-Dv=Avd                                      (27).

Subsequently, whether Avf is greater than Avd is determined in the step#132. If Avf≦Avd, the aperture value control data Avf is set slightlygreater than the flash available critical aperture value, the lightemission is sufficient so that the program flow goes to the step #133without indication of the out-of-range for the coupled operation withthe flash device. If Avf>Avd, which means that the light value isinsufficient for photographing due to the decreased aperture value,i.e., the aperture value is slightly smaller than the desired value, theprogram flow goes to the step #133 to calculate an intermediate aperturevalue Av by the followng equation

    (Avf+Avd)/2=Av                                             (28)

Also the warning lamp RA is lit to indicate that the aperture value Avfis out-of-the-flash-available range for photographing with the flashdevice coupled.

Subsequently, whether Av is smaller than Avo is determined in the step#135. If Av ≦Avo, the value Avo is used for the aperture value controldata Avf, however, if Avd≦ Avo, the value Av is used as Avf and theprogram flow goes to the step #138, wherein

    Iv.sub.max +Sv-Avf=Dv.sub.max                              (29-1)

is calculated. And in the step #139,

    Iv.sub.min +Sv-Avf=Dv.sub.min                              (29-1)

is calculated.

The value Dv_(max) shows the maximum flash available distance for theaperture value Avf and the Dv_(min) shows the minimum flash availabledistance. These data Dv_(max) and Dv_(min) are transferred to the flashdevice F1 through the flash control device FC so as to display the TTLmode operation which means that the light emission of the flash deviceis controlled on the basis of the light measurement value of the lightsensing element PD1 in the camera as hereinafter described. The valueIv_(min) shows the minimum amount of light of the flash device. Thevalue Iv_(min) may be read from a memory.

In the step #140, the number of steps of decreasing aperture size Avf iscalculated by the equation

    Avf-Avo=ΔAvf                                         (30)

In the step #141, an exposure difference value ΔEv is calculated by thefollowing equation

    (Ev+1)-(Avf+Tvf)=ΔEv                                 (31).

The exposure difference value ΔEv thus calculated is displayed by thedisplay device DPl shown in FIG. 4. The value ΔEv shows the differencebetween the actual exposure value of the object and the desired exposurevalue thereof.

In the step #142, whether the value ΔEv≧0 is determined. If ΔEv≧0, i.e.,Ev≧10 in case of FIG. 8, since the fill-in flash mode is set, the outputterminal 011 is made "High" and the program flow goes to the step #145.If Δ Ev<0 is judged in the step #142, which shows the main flash lightmode, the output 011 is made "Low" and the program flow goes to the step#145.

In the step #145, whether the actual photographing distance Dv of theinterchangeable lens LE coincides with the maximum photographingdistance Dv∞ of the lens is determined, wherein the maximumphotographing distance Dv∞ means the distance shorter than theinfinitive position of the lens by a unit scale. The maximumphotographing distance is different from lens to lens, so that themaximum photographing distance data is provided from the lens in use tothe camera as fixed data.

If Dv≧Dv∞ is determined in the step #145, there is a great possibilityof an underexposure even if the flash light is used, since thephotographing distance is set around infinity the flash device isuseless so that the program flow goes to the step #146 to light thedisplay lamp FIP to warn of the above matter, whereby the program flowgoes to the step #37. If Dv<Dv∞, the program flow goes to the step #37directly.

In the operations described above, the overexposure warning,underexposure warning, out-of-the-range-of-the-flash-available operationwarning and infinity distance warning is made by making the outputterminals 01 through 04 "High", respectively. When such warning is notnecessary, the output terminals are made "Low".

The device shown in FIG. 4 is explained with reference to the flow chartshown in FIG. 7.

In the step #38, whether a charge completion signal is applied to theCPU 1 from the flash device FL is determined. The charge completionsignal is generated when the main capacitor provided in the flash deviceFl is charged with the predetermined voltage sufficient to ignite theflash device. If the chrage completion signal is present, the displaydevice DPl indicates the exposure time control data Tvf, aperturecontrol data Avf and the exposure difference data ΔEv and the fact thatthe camera system is set in the flash light mode.

Subsequently, the output terminal 010 is made "High", and the distancedata Dv_(max) and Dv_(min) determined in the steps #138 and 139 aretransferred to the flash device FL from the flash control device FC, andthe CPU 1 waits for the "Low" signal a the input terminal 15. When thetransfer of the data is completed, the input terminal 15 is made "Low"so that the program flow goes to the step #42 causing the outputterminal 010 to be "Low", thereby going to the step #44. If the chargecompletion signal is absent, the program flow goes to the step #43 todisplay that the camera system is set in the ambient light mode and theexposure control mode, exposure time control data Tvc, aperture controldata Avc and the exposure difference ΔEv are indicated by the displaydevice DPl. Then the program flow goes to the step #44 to enable theinterrupt operation for the exposure control operation.

The program flow returns to the step #1 to determine whether the inputterminal ST is "High" due to closure of the light measurement switch MS.If the terminal ST is "High" the program flow goes to the step #7. Onthe other hand, if the terminal ST is "Low", the program flow goes tothe step #2 to determine whether the input terminal I2 is "Low". In acase where the exposure operation is ready and the film is not advanced,therefor the shutter is not in the charged position, the switch CS isset in a open state whereby the input terminal I2 is "Low", the programflow goes to the step #4 wherein a signal BLANK for disabling thedisplay device DPl is output and in the step #5, the interrput operationis disabled stopping the CPU 1.

However, when the film is already advanced and the shutter is alreadycharged, the switch CS is closed to make the input terminal I2 "High",so that the program flow goes to the step #3, wherein whether thecontent of the timer register TR is a predetermined value K isdetermined. The value K is for example 15 seconds. If the content of thetimer register TR is larger than the value K, the program flow goes tothe step #4, but if the content of the timer register TR is smaller thanthe value K, 1 is added to the content of the timer register TR, thenthe program flow goes to the step #8 to repeat the operation describedabove.

By the arrangement described above, while the light measurement switchMS is closed, read-in operation, calculation and display are continued.The same operation is continued until the content of the timer registerTR reaches the value K when the light measurement switch MS is open withthe film advanced and the shutter set in the charged position. When thelight measurement switch MS is open and the predetermined time intervalhas passed, the read-in operation, calculation and the display arestopped.

When the light measurement switch MS is closed and the first calculationoperation is completed the CPU 1 is enabled to receive the interruptionsignal at the input terminal IT. When the release switch RS is closed insuch state that the film is advanced and the shutter is set in thecharged position, the output of the AND gate AN1 is "High" to apply theinterruption signal to the input terminal IT, whereby the program flowgoes to the step #50 to effect the exposure control. In the step #50,the signal BLANK is output to disable the display device DPl. Then theprogram flow goes to the step #51 to make the output terminal 06 "High"to prevent the read-in operation of the data of the lens LE in the CPU 1from the interface IF during the read-in operation of the data in theinterface IF from the lens circuit LEC. If the interruption signal isapplied to the CPU 1 during the read-in operation of the data of theflash device FL to the CPU 1, the CPU 1 refuses the interruptionoperation until the input terminal i4 changes to "Low" from "High". Whenthe input terminal i4 becomes "Low", the output terminal 09 is made"Low" and then the program flow goes to the step #54.

In the step #54, in a case where the data is transferred to the flashdevice FL from the flash control circuit FC, when the interruptionsignal is applied to the CPU 1, the CPU 1 waits until the input terminali5 changes to "Low" from "High". When the input terminal i5 becomes"Low", the program flow goes to the step #55 to make the output terminal010 "Low". Then the program flow goes to the step #56 to make the outputterminal 08 "High" and the CPU 1 determines whether the chargecompletion signal is applied to the flash control device FC from theflash device FL. If the charge completion signal is detected by thechange of the state of the input terminal i6 to "Low", the program flowgoes to the step #58 causing the output terminal 08 to be "Low", and inturn whether the input terminal i7 is "High" is determined in the step#59. The input terminal i7 is "Low" or "High" depending on the absenceor presence of the charge completion signal.

When the "High" on the terminal i7 is detected, the step number of theaperture decreasing value Avf calculated in the steps #30 and 36 isoutput from the output port OP2 to the aperture control device CA in thestep #60. Then the exposure time control data Tvf is output from theoutput port OP1 to the exposure time control device CT in the step #61.

However, if the charge completion signal is absent, and therefore "Low"on the terminal i7 is detected in the step #59, the program flow goes tothe steps #62 and 63 to derive the step number of the decreasingaperture value ΔAvc for photographing under the stationary light and theexposure time control data Tvc.

As described above, according to the preferred embodiment of the presentinvention, whether the charge completion signal is present is determinedimmediately before the shutter SHT begins releasing, the control datafor the flash light Photographing or the data for the ambient lightphotographing are selectively output depending on the presence orabsence of the charge completion signal.

Subsequently, the terminal 05 is made "High" in the step #64 to startthe release circuit RL ad a "Low" signal is fed to the base of thetransistor BT1 through the inverter IN3 to continue the conductive stateof the transistor BT1 even if the light measurement switch MS is open.By the operation of the release circuit RL the exposure control device 3in FIG. 4 starts, whereby an aperture size control ring is rotated, sothat a pulse train is generated from the pulse generator PG, the numberof pulses being proportional to the amount of the rotation of theaperture size control ring. The aperture control device CA counts thenumber of the pulses, whereby the aperture size control ring is rotateduntil the counted number of pulses coincides with the diaphragm aperturesize decreasing value ΔAvc or ΔAvf for controlling the actual aperturevalue.

In a case where the single lens reflex camera is used, a reflectionmirror RM is raised as shown in FIG. 7. When the reflection mirror RM ismoved to the raised position, and the setting of the diaphragm apertureis completed, the shutter starts running and the exposure time controldevice CT begins counting the exposure time on the basis of the data fedfrom the terminal OP1 of the CPU 1.

In a case where the camera system is set in the flash lightphotographing mode, at the time when the shutter SHT is completelyopened, a flash light start signal is applied to the terminal JF3 of thefalsh device FL from the terminal JB7 of the flash control device FC toeffect the light emission of the flash device. If the flash device isset in the TTL mode, when the integration value of the light value onthe film plane measured by a light measuring circuit reaches thepredetermined value, a flash stop signal is aPplied to the terminal JF1of the flash device FL from the terminal JB5 to stop the flash deviceFL. When the time counted by the exposure time control device CT reachesthe exposure time control data fed from the output terminal OP1 of theCPU 1, the rear curtain of the shutter SHT starts, regardless of whetherthe flash light photographing mode or ambient light photographing modeis set in the camera. Upon completion of the running of the rear curtainof the shutter SHT, the switch CS is opened, and the reflection mirrorMR is dropped with the diaphragm aperture set at the open aperturevalue.

After the exposure control as described above, the output of theinverter IN5 becomes "Low" with the input terminal i3 of the CPU 1"High" causing the output terminal 05 to be "Low" in the step #66 sothat the release circuit RL is stopped and the transistor BT1 becomesnonconductive.

In the step #67, the interruption signal at the terminal IT is disabledand the program flow returns to the START. In this case if the lightmeasurement switch MS is in the closed position, data read-in,calculation and the display operations are performed again.

If the switch CS is opened, the output of the AND gate AN1 is "Low" soas to prevent the application of the interruption signal to theinterruption terminal IT of the CPU 1, thereby preventing the exposureoperation even if the release switch RS is closed. In this case dataread-in, calculation, and display operations are possible.

The detailed circuit arrangements of the flash control device FC and theflash device FL are shown in FIG. 17. Referring to FIG. 15, upon closureof the main switch MAS, the DC power is supplied to the flash device FLfrom the battery FB and the power ON reset signal PRO3 is output fromthe terminal PR3 of the power ON reset circuit PO3 to reset the flashdevice FL.

When the change over switch SSI is switched to the CU contact, the flashdevice FL is set in the first flash light photographing mode. In thiscondition, the output of an inverter IN14 is "Low" and the output of aninverter IN15 is "High", so that the output of an OR gate OR18 is"High", thereby a transistor BT8 conducts to effect the boostingoperation of the booster DD.

However, when the change-over switch SSl is switched to the EX contact,the flash device FL is set in the second flash light photographing mode.The output of an inverter IN15 becomes "Low" and the output of the ORgate OR14 becomes "High" by the power ON reset signal PR3. The output ofthe OR gate OR14 resets a flip-flop circuit FF11, thereby causing theoutput of an OR gate OR18 to be "Low". Under this condition, the boosterDD is not enabled even if the main switch MAS is closed. In order toenable the booster DD under the flash light photographing mode, thefollowing procedure is taken. By closure of the light measurement switchMS in the camera, the transistor BT1 conducts to allow the DC powersupply to the power ON reset circuit PO2 from the battery BB provided inthe camera. Thus, the power ON reset circuit PO2 supplies the power ONreset signal PR2 to the flash control circuit FC to reset the latter(FIG. 4). With reference to FIG. 13b and continuing reference to FIG.13a, upon closure of the light measurement switch MS, the output of theinverter IN2 becomes "High", thereby causing a one shot circuit OS1 toproduce a "High" pulse. The output pulse of the one shot circuit OS1 issupplied to the set input terminal of the flip-flop circuit FF11 throughthe OR gate OR6 and the terminals JB5 and JF1. The flip-flop FF11 is setby the pulse and an OR gate OR18 produces a "High" signal, which is fedto the base of the transistor BT8 which is then conductive, whereby thebooster DD is enabled. Also, the "High" pulse input from the terminalJF1 is applied to the input terminal of the timer T1 to start countingtime, which generates an output when a predetermined time period, forexample, 0.5 seconds has passed after reception of the "High" pulse. Theoutput signal of the timer T11 is applied to the reset input terminal ofthe flip-flop FF11 to make the Q output of the flip-flop FF11 and theoutput of an OR gate OR18 "Low", thereby causing the transistor BT8 tobe nonconductive. Then the booster DD is disabled to save the DC power.The timer T11 may be reset and start the time counting each time whenthe "High" pulse is applied to the timer from the terminal JF1. Also thetimer T11 may be reset when a sufficient time such as 10 minutes haspassed after the "High" pulse is applied to the timer from the terminalJF1.

When the flip-flop FF11 is set, a flip-flop FF10 and a D-type flip-flopDF10 are in the reset state, therefore the output terminal of a NOR gateNOI is "High". Also as hereinafter described, the output of a NAND gateNA1 is "High" such that the output of an AND gate AN22 and an OR gateOR21 are "High". In such states, if the flash device FL is set in thesecond flash light photographing mode with the switch SSl changed to theEX contact, both input terminals of an AND gate AN24 receive "High"signals, thus an OR gate OR22 outputs a "High" signal to the base of thetransistor BT6 causing the transistor BT6 to be conductive. Also atransistor BT7 is then made conductive to produce a "High" signal whichis supplied to the flash control circuit FC through the terminals JF2and JB6.

With reference to FIGS. 13a and 13b, in a state that the lightmeasurement switch MS is closed, when the output terminal 09 of the CPUbecomes "High", a one shot circuit OS2 generates a pulse. Then aflip-flop FF1 is set by the positive edge of the pulse and the counterCOl is also reset. A D-type flip-flop DF1 acts to generate a series ofpulses in response to application of the positive edge of each of pulsesDP fed from a frequency divider DV provided in the flash control circuitFC. The pulse DP has a period shorter than the time interval set in thetimer T11. A pulse is applied to the terminal JF1 of the flash device FLfrom an AND gate AN2 through an OR gate OR6 and the terminal JB5 of theflash control circuit FC every time the Q output of the flip-flop DF1becomes "High". The output pulses of the AND gate AN2 are applied to thecounter COl. A one shot circuit OS3 generates a pulse every time the Qoutput of the flip-flop DF1 becomes "High", and an inverter IN7 reversesthe output of the flip-flop DF1, then in turn a NAND gate NA5 applies aseries of "High" pulses to the base of a transistor BT10 in response tothe "Low" signals of the inverter IN7, whereby the transistor BT10 ismade conductive corresponding to the period of time during which each ofthe pulses of a NAND gate NA5 becomes "High". The terminals JB6 and JF2are made "Low" when the transistor BT10 is in the conductive state.

With further reference to FIG. 14, upon application of the "Low" signalsto the terminal JF2 from the transistor BT10 in the flash lightphotographing mode, the "Low" signals are applied to an inverter IN20and an AND gate AN25 generates a pulse train supplied from the inverterIN20. The output FR of the AN gate AN25 and the pulses DP on theterminal JF1 are applied to the input terminals of an AND gate AN10 toreset the flip-flop FF10 resulting in generation of a "High" signal onthe Q output of the flip-flop FF10. The Q output of the flip-flop FF10is applied to a NOR gate NO1 which generates a "Low" signal to an ANDgate AN22 to make the output of the AND gate AN22 "Low".

The output of the flip-flop FF10 is applied to the intput terminal of anAND gate AN11. Thus, the AND gate AN11 gates the signals applied from anOR gate OR12 to the base of the transistor BT6 through OR gates OR13,OR21, an AND gate AN24 and the OR gate OR22, whereby the transistors BT6and BT7 are made conductive to produce "Low" signals. By the operationdescribed above, the output data of the OR gate OR12 is transferred tothe terminal JB6 through JF2.

A counter CO3 for counting the number of pulses applied to the terminalJF1 is adpated to be reset by the output FR of the AND gate AN25. Adecoder DE2 provides the output data shown in Table 3 on the outputterminals b0 through b8 corresponding to the data applied to the inputterminals CF0 through CF3. The output terminal b0 of the decoder DE2 ismade "High" during a time interval between two falling points of thefirst pulse and the second pulse on the terminal JF1. The "High" signalon the output terminal b0 is applied to the one input terminal of an ANDgate AN70, another input terminal of which receives the chargecompletion signal CD. The AND gate AN70 gates the charge completionsignal CD upon receipt of the signal on the terminal b0, in other words,the charge completion signal can be transferred to the terminal JF2 whenthe terminal b0 is "High". The charge completion signal CD on theterminal JF2 is transferred to the serial input terminal SI of a shiftregister SR1 through the terminal JB6 of the flash control circuit FCand an AND gate AN3 (FIG. 13a and 13b). The shift register SR1 takes thedata fed from the AND gate AN3 when the second pulse is applied to theterminal CL from the AND gate AN2.

With continuing reference to FIG. 14, the terminal b1 of the decoder DE2is made "High" during a time interval between two falling points of thesecond pulse and the third pulse on the terminal JF1. The output of theterminal b1 is applied to one input terminal of an AND gate AN71 anotherinput terminal of which receives a signal from IN13 representing whichof the TTL mode or the external light mode is selected. When the TTLmode is selected a switch MOS is switched to the TT contact so that aninverter IN13 generates a "High" output, on the other hand, when theexternal light mode is selected, the switch MOS is switched to the OUcontact so that the inverter IN13 generates a "Low" signal. The outputof the inverter IN13 is transferred to the shift register SR1 throughthe terminals JF2 and JB6 and stored therein in a similar manner asdescribed above.

A decoder DE3 is adapted to receive the output data of a first dataoutput device GS and the data of a second data output device PS toprovide one of the maximum light emission value Ivmax of the flashdevice FL at the terminals G0 through G3, the contents of which areshown in the Table 4. The output of the decoder DE3 can also betransferred to the shift register SR1 through AND gates AN72 throughAN75 which receive the output signals on the terminals b2 through b5.

The first data output device GS is coupled with an adjusting member foradjusting a light distribution characteristic by changing a positionalrelationship relative to a light reflection plane for the flash lightand generates various data. The second data output device PS generatesdata representing the kind of reflection panel used in the flash devicefor emitting the flash light. In the preferred embodiment, either thewide angle reflection panel or the normal reflection panel isalternatively used. The decoder DE3 provides the maximum light emissionvalue Ivmax shown in the Table 4 on the basis of the output data of thefirst output data output device GS and the second data output device PS.

A decoder DE4 provides the aperture values set in the flash device FL bythe data input from an aperture value data output device APS which iscoupled and moved with an adjusting member for adjusting the aperture APdisposed in front of the Photo transistor PT used in the flash device FLso as to adjust the incident light value. The contents of the decoderDE4 are shown in the Table 5.

The output terminals F0, F1 and F2 of the decoder DE4 can be transferredto the shift register SR1 through AND gates AN76 through AN78 which areenabled by the output signals of the terminals b6 through b8 of thedecoder DE2.

When the tenth pulse applied to the counter C03 falls, the terminal b8of the decoder DE2 becomes "Low" to reset the flip-flop FF10 through anOR gate OR11 to cause the Q output of the flip-flop FF10 to be "Low",thereby causing the output of the AND gate AN11 to be "Low" with theoutput of the NOR gate NO1 being "High", resulting in making theterminal JF2 of the flash device FL "High".

Upon application of the tenth pulse DP to the decimal counter COl (FIG.13), a carry signal is generated at the carry terminal CY. The carrysignal is fed to the reset terminal R of the flip-flop FF1 and the resetterminal RE of the D-type flip-flop DF1, then flip-flops FF1 and DF1 arereset so that both the Q output terminals become "Low". Both of the ANDgates AN2 and AN3 are disabled by the "Low" signal of the D-typeflip-flop, then the read-in operation of the data Iv_(max) and the setaperture value Av into the shift register SR1 is stopped.

When the input terminal i4 of the CPU 1 becomes "Low" by the Q output ofthe flip-flop FF1 the CPU 1 determines that the read-in operation of thedata from the flash device FL to the flash control circuit FC iscompleted (FIG. 4). Also the data in the shift register SR1 istransferred to the input terminal IP7 of the data selector MP1 and inturn the data is transferred to the CPU 1 in the order designated by thesignals applied to the temrinal SL of the data selector MP1 from the CPU1.

In the preferred embodiment, the shift register SR1 is 9 bits, so thatthe data in the shift register SR1 can be read out separated in two orthree groups if the number of bits of the CPU is small.

In a case where the flash device FL is not attached to the camera or theflash device is attached to the camera but the power switch MAS is OFF,the contents of the shift register SR1 are zero. Thus by determining thecontents of the shift register SR1, whether or not the flash device isattached to the camera and the power switch MAS is OFF can be detectedby the CPU 1.

In a case where the flash device FL is set in the first flash lightphotographing mode with the switch SS1 changed to the CU contact, theoutput of an inverter IN14 is "Low", so that the AND gate AN24 isdisabled to prohibit transfer of the maximum light emission data Ivmaxand the set aperture value Av from decoder DE4 to the shift register SRIthrough the terminals JF2 and JB6. As the switch SS1 is in the CUposition the output of an inverter IN15 is "High", then the "High"signal is applied to one input terminal of the AND gate AN20. If thecharge completion signal CD is "High", the output of the AND gate AN20is "High". On the other hand, if the X contact of the flash device isopened, the output of an AND gate AN26 is "Low" with the output of aninverter IN16 "High". Accordingly, the output of an AND gate AN23 is"High". The output of the AND gate AN23 is applied to the base of thetransistor BT6, whereby the transistor BT6 and BT7 conduct. By thisoperation only the charge completion signal is applied to the flashcontrol circuit FC through the terminals JF2 and JB6 and stored in theshift register SR1 in the first flash light photographing mode.

As shown in the Tables 4 and 5, the data is so arranged that all of thedata which is read in the shift register SR1 is not "high", therefore itis possible to determine that the mode set in the flash device is thefirst flash light photographing mode.

A method of judgment of the mode set in the flash device FL by the CPU 1is explained hereinafter.

Whether the first flash light mode is ordered is determined, whereby, ifthe mode ordered is not the first mode, the program flow goes to thestep #101 in FIG. 11. However, if the ordered mode is the first mode,the exposure time is set to 1/250 sec and the aperture value is set bythe data set in the flash device, then the program flow goes to the step#140.

The following description is made to explain a way of transferring theflash available range data from the camera to the flash device.

Referring to FIG. 13, when the terminal 010 of the CPU 1 becomes "High",the "High" signal is applied to a one shot circuit OS4, which supplies apulse having a predetermined width to the set terminal of a flip-flopFF2 and the reset terminal RE of the counter C02. Then the Q output ofthe flip-flop FF2 is "High". This "High" signal is fed to the inputterminals of AND gates AN52 and AN4. The contents of the counter C02 iszero. The output of the one shot circuit OS4 is inverted by an inverterIN8 and the transistor BT10 is made conductive, whereby a "Low" signalis applied to the terminal JF2 of the flash device FL (shown in FIG. 14)from the terminal JB6 of the flash control device FC and the output ofthe AND gate AN25 is "High". As the input terminal JF1 is "Low", theinverter IN11 produce a "High" signal to the input terminal of an ANDgate AN15. Another input terminal of the AND gate AN15 receives a "High"signal from the output FR of the AND gate AN25. By the output of the ANDgate AN15, a pulse is applied to the set terminal of a flip-flop FF13 sothat the flip-flop FF13 is set, causing the Q output to be "High". This"High" output is applied to the input terminal of the D-type flip-flopDF10. The Q output of the flip-flop DF10 becomes "High" upon receipt ofa pulse at the terminal CL from oscillator FOS. The "High" signal at theQ output of the flip-flop DF10 is applied to AND gates AN16 and AN17.The AND gate AN16 gates the pulse train FCP fed from the oscillator FOSto both clock input terminals CL of a counter C04 and a shift registerSR2. Also the clock pulse train FCP is applied to the base of thetransistor BT6 through the OR gates OR13, OR21, OR22, and the AND gateAN24 so as to drive the transistor BT7, which feeds the pulse train tothe clock input terminal CL of the counter C02 through the terminal JF2,JB4, and the AND gate AN4 (FIG. 13a).

A one shot circuit OS11 generates a "High" pulse signal by the output ofthe D-type flip-flop DF10 to reset the shift register SR2 through an ORgate OR17 and the counter C04 is reset by the "High" signal appliedthrough an OR gate OR16.

With respect to FIG. 13a, the output of the counter C02 which is theresult of the counting of the clock pulse train FCP is input in thedecoder DE1 which generates a "High" signal on any one of the outputterminals a0 through an in the order corresponding to the counted valueof the counter C02.

When the first pulse of the pulse train FCP is input in the counter C02from the AND gate AN4, the output of the decoder DEl becomes "High" bythe positive-going edge of the first pulse. The "High" state iscontinued until the positive-going edge of the second pulse of the pulsetrain FCP. An AND gate AN60 is opened by the output of the decoder DE1to gate the most significant bit of the maximum flash available distancedata Dv to the terminal JB5 through the OR gates OR3 and OR6 and the ANDgate AN52. This data on the terminal JB5 is applied to the serial inputterminal SI of a shift register SR2 through terminal JF1 and the ANDgate AN17 (FIG. 14). The shift register SR2 takes the most significantbit of the data Dv_(max) synchronized with the negative-going edge ofthe first pulse of the pulse train FCP. In a similar manner as describedabove, the output terminal an of the decoder DEl becomes "High" with thepositive edge of the (n+1)th pulse of the pulse train FCP keeping the"High" state until the positive edge of the (n+2)th pulse. During thisperiod, the least significant bit of the minimum flash availabledistance data Dv_(min) is output from an AND gate AN6n and thisinformation is taken in the shift register SR2 synchronized with thenegative-going edge of the (n+1)th pulse.

Since the counter C04 is a (n+2) number system, the (n+2)th pulse of thepulse train FCP is output from the carry terminal CY and in turn thecarry output is applied to the reset terminals CL of the flip-flop FF13and the D-type flip-flop DF10 which are reset respectively, causing theAND gates AN16 and AN17 to be disabled. The shift register SR2 takes a"High" or "Low" signal in synchronism with the negative-going edge ofthe pulse FCP. However, the least significant bit of the shift registerSR2 is not applied to the display device DP2.

On the other hand, the counter C02 in the camera is a (n+2) numbersystem and all of the output of the counter C02 becomes "Low" with thepositive-going edge of the (n+2)th pulse of the pulse train FCP, wherebyall of the outputs a0 through an of the decoder DEl become "Low". Theflip-flop FF2 is reset when the terminal an goes "Low" by thepositive-going edge of the (n+2)th pulse, then the AND gate AN4 and AN52are disabled. Since the Q output of the flip-flop FF2 is connected withthe input terminal i5 of the CPU 1, so that the CPU 1 detects that thedata transfer is completed by the "Low" signal on the terminal i5.

In the flash device FL of FIG. 14, the display device DP2 displays theflash available range of the flash device by the data Dv_(max) andDv_(min) fed from the camera. A switch DS is provided for switching theunit contents of the display. Display device DP2 displays the flashavailable range distance data in terms of the metric system with theswitch DS switched to the m contact and displays the distance data interms of the foot-pound system with the switch DS switched to the ftcontact. The flash available range distance data can be displayed-by adisplay device DP5 (FIG. 13A). The display device DP2 is provided on thebackside of the flash device and the display device DP5 can be providedin a finder, top face or the back lid of the camera.

With reference to FIG. 13a, a timer circuit T15 generates an outputafter sufficient time has passed for transferring the data Dv_(max) andDv_(min) to the flash device FL from the period of generation of theoutput of the one shot circuit OS4. Thus, the timer circuit T15 resetsthe flip-flop FF2 through the OR gate OR2 after the period fortransferring the data has lapsed.

Detecting the charge completion signal is explained hereinafter.

Referring to FIG. 13, the terminal 08 of the CPU 1 becomes "High" uponclosure of the release switch RS. The "High" signal is applied to a oneshot circuit OS6, which generates a "High" pulse of a predeterminedwidth. A flip-flop FF3 is set by the output of the one shot circuit OS6to generate a "High" signal at the Q output terminal. The output of theflip-flop FF3 is applied to the D input terminal of a D-type flip-flopDF2 so that the Q output terminal of the flip-flop DF2 becomes "High"upon application of the clock pulse DP to the clock terminal CL of theflip-flop DF2 from the frequency divider DV. The Q output is applied toone input terminal of an AND gate AN6 which receives the clock pulse DPfrom the frequency divider DV at another input terminal, whereby the ANDgate AN6 gates the clock pulse DP to the terminal JF1 of the flashdevice FL through the OR gate OR6 and the terminal JB5 of the flashcontrol device FC.

The "High" signal at the Q output of the flip-flop DF2 is applied toanother one shot circuit OS10, which generates a pulse of predeterminedwidth to an inverter IN9. The NAND gate NA5 generates a pulse of "High"level the width of which corresponds to that of the output of the oneshot circuit OS10. The output pulse of the NAND gate NA5 is applied tothe base of the transistor BT10, which is conductive during the periodof the pulse of the NAND gate NA5. Accordingly, a pulse of "Low" levelis input to the terminal JF2 of the flash device FL through the terminalJB6 of the flash control circuit FC. The "Low" level pulse on theterminal JF2 is inverted by the inverter IN20 and applied to the inputterminal of the AND gate AN25, which generates a pulse output FR (FIG.14).

The pulse DP is applied to the set terminal of the flip-flop FF10 to setit, so that the Q output thereof is "High". The "High" signal of theflip-flop FF10 is inverted by the NOR gate NO1, then applied to theinput terminals of the AND gates AN11 and AN22.

The counter C03 in the flash device Fl counts one pulse DP and thecontent thereof becomes "0001", whereby the output terminal b0 of thedecoder DE2 becomes "High". This "High" signal is applied to the inputterminal of the AND gate AN70 which gates the charge completion signalCD to the terminal JF2. The charge completion signal on the terminal JF2is transferred to the terminal JB6 of the flash control circuit FC ashereinbefore described.

When the Q output of the flip-flop DF2 (FIG. 13b) becomes "High", thepulse DP from the frequency divider DV is applied to the reset inputterminal R of the flip-flop FF3 and the reset terminal RE of theflip-flop DF2, then the flip-flops FF3 and DF2 are respectively reset bythe negative-going edge of the pulse DP. Thus one pulse DP istransferred from the flash device FL to the flash control circuit FC.

After the "High" signal is input to the D-type flip-flop DF3 from theflip-flop DF2, the Q output of the flip-flop DF3 becomes "High" by thepositive-going edge of the pulse DP applied to the clock terminal CL ofthe flip-flop DF3. Also the Q output of the D-type flip-flop DF4 becomes"High" by the pulse DP. The "High" signal of the flip-flop DF3 isapplied to the input terminal of an AND gate AN7, which gates the chargecompletion signal applied from the terminal JB6.

An AND gate AN51 produces a "High" signal upon receipt of the "High"signal from the Q output of a D-type flip-flop DF4. The output of ANDgate AN7 is applied to the D input of D-type flip-flop DF5 and the ANDgate AN51 is applied to the clock input terminal of a D-type flip-flopDF5, the Q output of which becomes "High" upon receipt of the pulse DP.The "High" signal of the flip-flop DF5 :s applied to the input terminali7 of the CPU 1.

The output signal of the AND gate AN51 is input to the reset terminalsRE of the D-type flip-flops DF3 and DF4, then the Q output terminals ofboth DF3 and DF4 become "Low" respectively. The "Low" output of theflip-flop DF3 is applied to the input terminal i6 of the CPU 1 as thesignal representing that the read-in operation of the charge completionsignal is completed.

In the flash device shown in FIG. 14, when the flip-flop FF10 is set asdescribed above, a timer T18 starts time counting. The preset time ofthe timer T18 is longer than the time required for transferring thecharge completion signal from the flash device FL to the flash controlcircuit FC.

The timer TI8 generates a "High" signal when the preset time has lapsedand the "High" signal is applied to the reset input terminal of thecounter C03 through an OR gate OR10 and is applied to the reset terminalof the flip-flop FF10 through an OR gate OR11, whereby the counter C03and the flip-flop FF10 are simultaneously reset, so as to prevent theoutput 0001 of the counter from being held a long time.

In a case where the "High" signal on the terminal JF1 and the chargecompletion signal derived from detector CD are applied to the inputterminals of an AND gate AN18, the AND gate AN18 gates the output FR ofthe AND gate AN25 to the set input terminal of a flip-flop FF12 and aone shot circuit OS12. The flip-flop FF12 is set and the one shotcircuit OS12 generates an output the width of which is longer than thetime period of the pulse DP. By this arrangement, if a plurality ofpulses DP must be transferred from the terminal JF1 in series, each oneof the pulses DP can be transferred from the terminal JF1 within oneperiod of the output pulse of the one shot circuit OS12.

In a case where only one pulse DP is transferred to the terminal JF1after the release switch RS is closed, an AND gate AN19 does notgenerate an output so that the flip-flop FF12 is kept in the set state.Under such state if the switch SS1 is switched to the EX contact withthe output of the inverter IN14 being "High", this "High" signal isapplied to one input terminal of an AND gate AN26 through an OR gateOR20 and the AND gate AN21. Accordingly, when an order signal of thelight emission is applied to the terminal JF3, the order signal istransferred to the flash light emission control device FLC through theAND gate AN26. Therefore, in the second mode and when the chargecompletion signal is present, the flash device FL is ready for lightemission upon closure of the release switch RS.

When the X contact SX in the flash control device FC of FIG. 13a and 13bis closed, an inverter IN17 of FIG. 14 drives a one shot circuit OS13which generates a "High" output pulse. The "High" output pulse istransferred to the light emission control circuit FLC through AND gateAN26 thereby causing a xenon tube XE to emit the flash light in a knownmanner. On the other hand, by the output of the one shot circuit OS13, a"Low" level pulse appears on the terminal JB6 through terminal JF2. Aninverter IN10 (FIG. 13a) generates a "High" signal which is applied toan AND gate AN8. If the shutter button has already been pressed, a"High" signal is generated from the output terminal 05 of the CPU 1, the"High" signal is applied to an AND gate AN8. Then the AND gate AN8provides a "High" signal to a flip-flop FF5 to set it, thereby the Qoutput of the flip-flop FF5 becomes "High". The Q output of theflip-flop FF5 is applied to one input terminal of an AND gate AN9 andthe base of a transistor BT4 which is then nonconductive.

A transistor BT3 receives a light value measured on the film plane by alight measurement circuit ME and produced from an operational amplifierOA1 (FIG. 4), whereby a current proportional to the light value of theflash light measured on a film plane flows through the collector of thetransistor BT3. The collector current is integrated in a capacitor C1. Avoltage across the capacitor C1 is applied to a comparator AC1 to whicheither a reference voltage CE20 or another reference voltage CE21 isapplied through analog switches AS20 or AS21 controlled by the signal onthe CPU output terminal 011. The terminal 011 becomes "High" for thefill-in flash mode and "Low" for the flash light mode, i.e., the flashlight is used as a main light source for photographing. Accordingly, inthe fill-in flash mode, the analog switch AS20 is ON so that thereference voltage CE20 is applied to the comparator ACl. In the flashlight mode, the analog switch AS21 is ON so that the reference voltageCE21 is applied to the comparator ACl. The ratio of the referencevoltage CE21 is applied to the comparator AC1. The ratio of thereference voltages CE20 and CE21 is 3:4, in other words, the referencevoltage CE20 is lower by 0.5 Ev than the reference voltage EC21 in termsof the apex value. Furthermore, the reference voltage CE21 correspondsto the correct exposure.

When the voltage across the capacitor Cl reaches the reference voltageCE20 in case of the fill-in flash mode, the comparator ACl generates a"High" output, so that the one shot circuit OS9 generates a "High"output. Under this condition if the signal indicating the TTL lightmeasuring mode is stored in the shift register SR1, a pulse istransferred to the terminal JF1 through the AND gate AN9, OR gate OR6and the terminal JB5 to stop the light emission of the flash device FL.In a similar manner described above, the flash device is stopped whenthe voltage across the capacitor Cl reaches the reference voltage EC21in case of the flash light mode. As described above, in case of thefill-in flash mode, when the light exposure value measured on the filmplane reaches the value smaller by 0.5 Ev than the correct exposurevalue, the light emission of the flash device FL is stopped, thisoperation corresponds to the case wherein the value k1 is set by 0.5 Evas described with reference to FIGS. 1 and 2.

The output pulse of the AND gate AN8 is applied to the timer TI10. Thetimer TI10 generates a pulse when a sufficent time has passed after theflash device FL completes the light emission, so that the flip-flop FF5is reset, thereby causing the transistor BT4 to be conductive resultingin disabling the AND gate AN9. Also the flip-flop DF5 is reset.

In the flash device FL, the AND gate AN26 produces a "High" pulse by theoutput of the one shot circuit OS13, whereby a flip-flop FF14 is set andthe Q output thereof becomes "High". In a case where the switch MOS isswitched to the OU contact, i.e., the external light mode is set in theflash device, inverters IN18 and IN19 generate "High" outputs.Therefore, the output of a NAND gate NA2 is "Low", whereby a transistorBT5 is non-conductive and an AND gate AN28 is enabled.

By emitting the flash light from the xenon tube XE a phototransistor PTreceives light reflected from the photographic object through thediaphragm aperture AP. The output current of the photo transistor PT isintegrated by capacitor C2. When the voltage across the capacitor C2reaches a reference voltage VE2, which is variable and determinedcorresponding to the film sensitivity used in the camera, a comparatorAC2 provides a "High" output to enable a one shot circuit OS14. Theoutput pulse of the one shot circuit OS14 is transferred to the flashlight control circuit FLC, whereby the xenon tube XE stops emission ofthe flash light.

In case of the TTL mode with the switch MOS switched to the TT contact,an inverter IN40 generates a "High" signal to enable an AND gate AN27,whereby the light emission stopping signal transferred to the terminalJF1 of the flash device Fl from the one shot circuit OS9 is furthertransferred to the flash light control circuit FLC through the AND gateAN27 and an OR gate OR24.

When the order signal for emission of the flash light is applied to atimer T12 from the AND gate AN26, the timer T12 counts the period oftime required for the full light emission of the xenon tube. When thetime set in the timer T12 has lapsed, the output of the timer T12 isapplied to the reset terminal of a flip-flop FF12 through the OR gateOR19 to reset it. The output of the time T12 is also applied to thereset terminal of a flip-flop FF14 to reset it.

In a case where the first flash light photographing mode is selectedwith the switch SS1 switched to the CU contact, the output of theinverter IN15 is "High". If the charge completion signal is present, theAND gate AN20 and the OR gate OR20 generate "High" signals respectively,whereby the AND gate AN26 is enabled. In the state described above, withthe X contact opened, an AND gate AN23 is enabled by the output of theinverter IN16 to gate the charge completion signal to the terminal JF2through the OR gate OR22 and the transistors BT6 and BT7. The chargecompletion signal is read in the flash control circuit FC, then thefirst flash light photographing mode is detected.

Upon closure of the X contact SX, the AND gate AN26 generates a "High"signal by the output of the one shot circuit OS13 and in turn the outputof the inverter IN16 is made "Low". The "Low" signal is transferred tothe terminal JB6 of the flash control device FC through the terminal JF2as the order signal of the flash light emission. In case of the TTLmode, the light emission stopping signal from the flash control circuitFC is transferred to the flash light control device FLC through the ANDgate AN27 and the OR gate OR24. In case of the external light mode, thelight emission stopping signal from the one shot circuit OS14 is appliedto the flash light control device FLC through the OR gate OR24 to stopthe emission of light by the xenon tube XE.

In order to display that the light control is completed by the output ofthe one shot circuits OS9 and OS14, there is provided a display deviceFDC1 in the flash control circuit FC and another display device FDC2 inthe flash device FL. In the flash control device FC of FIG. 13a, whenthe AND gate AN9 is enabled by the content of the shift register SR1showing the TTL mode, and when the light emission stopping signal isgenerated, the display device FDC1 displays whether the light controlperformed in the camera system is correct for a predetermined period. Onthe other hand, in the flash device, when the light emission stoppingsignal is generated from the OR gate OR24, the display device FDC2displays an indication confirming that the light value is controlledcorrectly.

A detailed circuit arrangement of the display device will be describedhereinafter.

Referring to FIG. 15, a switch ASS for setting the diaphragm aperturevalue is connected through an inverter IN80 with one input terminal ofan AND gate AN90, the output of which is connected with the clock inputterminal of a counter CO30 with another input terminal of the AND gateAN90 connected with the output of a frequency divider FDV1, so thatduring closure of the switch ASS, the output of the inverter IN80becomes "High" and the AND gate AN90 is enabled to pass the clock pulsetrain from the frequency divider FDV1 to the counter CO30, which countsthe number of clock pulses applied thereto during the closure of theswtich ASS. The number of the pulses counted by the counter CO30corresponds to the set aperture value.

A switch SSS for setting the film sensitivity is connected through aninverter IN81 with one input terminal of an AND gate AN91, the output ofwhich is connected with the clock terminal of a counter CO31 withanother input terminal of the AND gate AN91 connected with the outputterminal of the frequency divider FDVl, so that during the closure ofthe switch SSS, the AND gate AN91 allows the clock pulse train to passto the counter CO31 to increase the contents thereof, whereby thecontent of the counter CO31 represents the film sensitivity.

The shift register SR2 also shown in FIG. 14 for storing the data Avf,Dv and Sv is connected with a data selector MP10, and also to a decoderDE8 having output terminals r0 through rn. The decoder DE8 outputs a"High" signal at any one of the terminals r1 through r.sub. n-1 uponreceipt of the photographing distance Dv which is in the flash availabledistance range. If the photographing distance Dv is shorter than theflash available distance range, the decoder outputs a "High" signal atthe terminal Un. If the photographing distance Dv is longer than theflash available distance range, the decoder DE8 outputs a "High" signalat the terminal uo. If every bit of the photographing distance Dv is 1,the terminals r1 through r_(n-1) become "High".

In a case where the flash device FL is attached to the camera, a dataselector MP10 outputs the aperture value Avf and the film sensitivity SVfed from the shift register SR2 upon receipt of the "High" signal of theQ terminal of the flip-flop FF11 shown in FIG. 14B.

In a case where the flash device Fl is not attached to the camera, thedata selector MP10 outputs the manually set aperture value Avf and thefilm sensitivity SV fed from the counters CO30 and CO31 by the "Low"output of the flip-flop FF11.

The aperture setting data output from the data selector MP10 is decodedin a decoder DE5 for display in a display DE5 and the film sensitivitydecoded by decoder DE6 and is displayed by the display unit DP11 indigital form.

A display unit DP13 is provided for displaying whether or not the flashdevice FL is attached to a camera exclusively used for that flash devicein response to the Q output states of the flip-flop FF11.

Another display unit DP15 is provided for displaying either the flashlight control mode for the TTL light measurement if the output of theAND gate AN79 is "High" or the flash light control mode under theexternal light measurement if the output of the AND gate AN79 is "Low".

The film sensitivity fed from the data selector MP10 is converted intoan analog form by a digital/analog converter DA and in turn the analogdata is logarithmically expanded by an arithmetic circuit ALC, thenapplied to an inverting input terminal of the comparator AC2 shown inFIG. 14. By this arrangement, the reference voltage source VE2 can beomitted.

Another advantage of this arrangement is that since the flash light iscontrolled by the content of the shift register SR2 storing the filmsensitivity set by the camera, so far as the flash device FL is attachedto the camera for exclusive use, a correct exposure is assured even if awrong film sensitivity is set in the flash device FL.

A ROM R02 is provided for producing a flash available distance range onthe basis of the aperture value Avf, the film sensitivity fed from thedata selector MP10 and the maximum light emission value of the flashdevice FL fed from the decoder DE3.

A switch PAS is closed or ON when the light emitting direction of theflash device is changed for correcting the parallax between the axis ofthe photographic lens of the camera and the light axis of the xenon lampin case of close up photographing.

The switch PAS is connected with an inverter IN82, the output of whichis connected with a display unit DP14 and the ROM R02. When the switchis closed, the output of the inverter IN82 becomes "High" so that thedisplay unit DP14 displays the parallax correction.

It is noted that when the parallax correction is made, the effectivelight emission value of the flash device and the maximum flash availabledistance range change. Therefore, in a case where the parallaxcorrection is present and the switch PAS is closed, the ROM R02 outputsthe minimum photographing distance Dvmin calculated by the equation

    Iv.sub.min +Sv-Av=Dv.sub.min

wherein Ivmin is the minimum light value of the flash device.

Although the minimum high value Ivmin changes according to the lightdistribution characteristic and the kinds of the reflection panel of theflash device, the maximum light value data from the decoder may includethe light distribution characteristic and the information of the kind ofthe reflection panel. Because the ratio between the maximum light valueand the minimum high value of the xenon tube is constant, therefor themaximum light value fed from the decoder DE3 may correspond to theminimum light value when the parallax correction is present.Accordingly, when the values Sv and Av are determined, the address ofthe ROM R02 where the minimum light vlaue is stored can be accessed bythe values Sv and Av so as to output the minimum photographing distanceDvmin.

The ROM R02 may be designed to produce an output each bits of which are1 if all bits of the data Av are 1.

FIG. 16 shows a flow chart of a modification of the operation shown inFIG. 11.

In the step #260,

    Ivmax+Sv-Av=Dvmax

is calculated to obtain the maximum photographing distance Dvmax in thecoupled distance range. Then program flow goes to the step #261, whereinthe minimum photographing distance Dvmin is calculated by the equation

    Ivmin+Sv-Avf=Dvmin.

The minimum light value Ivmin of the flash device may be stored in thememory device in the camera as fixed data used commonly for variouskinds of flash devices.

In the next step #262, a desired light value Iv is calculated by

    Dv+Avf-Sv=Iv

under the photographic conditions at the time of the photographing.

The various data Avf, Sv, Dv, Iv, Dvmax and Dvmin are output at theoutput OP4 of the CPU 1 in step #263, then the program flow goes to thestep #140 and steps 37-43 also shown in FIG. 11. In this operation thevarious data required in the flash device can be obtained in the camera.

In the step #38, when the charge completion signal is not detected,ambient light photographing is displayed in the step #43, then theprogram flow goes to the step #40 so as to transfer the various datacalculated for the flash light photographing. Accordingly in thismodification, the data for displaying the flash light photographing canbe transferred to the flash device from the camera not only for flashlight photographing but also for ambient light photographing.

FIG. 17 shows the detailed circuit arrangement of the interface IF andthe lens circuit LEC.

The ROM RO in the lens circuit LEC stores the following data. The Table6 shows the specific technical meaning of the data stored in the ROM ROand the Table 7 shows the address of the data stored in the ROM RO.

The data "11100" in the address "00000001" is used to check whether aninterchangeable lens is attached to the camera. The data "11100" can becommonly used for all kinds of lenses. The opened aperture value Avo isstored in the address "00000010" and the maximum aperture value Avm isstored in the address "00000011". The shortest focal length fw of thezoom lens is stored in the address "00000100". If the lens used is afixed focal length type, the fixed focal length may be stored in thisaddress. The longest focal length ft of the zoom lens is stored in theaddress "00000101". For the fixed focal length lens, the data "11111" isstored in the ROM RO. The maximum distance data Dv is stored in theaddress "00000110".

The photographing distance data of variable value is stored in theaddresses "00010000" through "00011111". The set focal length data arestored in the addresses "00100000" through "00101111".

A distance information unit DS produces data of 4 bits representing anamount of the rotation angle of a distance adjusting ring (now shown) ofthe camera relative to the infinity position. The ROM RO can be accessedby designating the lower four bits r3 through 40 of the address datawith the output data of the distance information unit DS so as toproduce the distance data from the ROM. An example of lens data is shownin the Table 8. As understood from Table 8, a distance data "11001"corresponding to Dv=8.5 can be produced from the ROM if the distanceadjusting ring is set at a position between the infinity position and17m, so that the distance information unit DS produces the data "0000".In case of flash light photographing, if the data "11001" is input inthe CPU 1, the infinity warning can be displayed by a display device FIPin FIG. 4.

By increasing the number of bits of the address data and the distancedata stored in the ROM, the interval of each of the distance ranges canbe decreased and the total number of the distance ranges can beincreased.

The focal length data set for the zoom lens are stored in the addresses"00100000" through "00101111". For a fixed focal length lens, the data"11111" is stored in all the addresses mentioned above.

A focal length information unit FS produces the data of 4 bitsrepresenting the amount of movement of a zoom ring of a zoom lens fromthe shortest focal position. The ROM RO can be accessed by designatingthe lower 4 bits r3 through r0 of the address data with the output dataof the focal length inforamtion unit FS to produce the focal length data(absolute value) from the ROM RO.

The operation of the interface IF will be described hereinafer. A oneshot circuit OS30 produces a "High" signal from the output of the "High"signal on the output terminal O5 of the CPU 1. The "High" signal of theone shot circuit OS30 sets a flip-flop FF30 such that the clock pulsetrain CPL is applied to the clock terminal of a D-type flip-flop DF30from the oscillator OSC (FIG. 4) through an AND gate AN30. Then the Qoutput of the flip-flop DF30 becomes "High" in synchronism with thepositive-going edge of the clock pulse, so that counters CO10, CO11 andCO12 are released from a reset condition, whereby decoders DEll and DE12are enabled to output the data. The clock pulse train is also applied tothe terminal JL2 of the lens circuit LEC through the terminal JB2 of theinterface IF. The DC power is supplied to the terminal JL1 of the lenscircuit LEC from the terminal JB1 of the camera upon conduction of thetransistor BT2 by the "High" output of the terminal 06 of the CPU 1,thus, the power ON reset P04 generates a pulse. A flip-flop FF35 and aD-type flip-flop DF31 are reset and a flip-flop FF34 is set by thepositive-going edge of the output pulse of the power on reset P04. The Qoutput of the flip-flop DF31 becomes "High" by the negativegoing edge ofthe first clock pulse CPL, whereby counters CO15 and CO16 are releasedfrom the reset condition, resulting in enabling the decoder DE15,whereby the data transferring becomes ready.

The counter CO10 and the decoder DEll in the interface IF and thecounter CO15 and the decoder DE15 in the lens circuit LEC are providedfor generating the timing signals for synchronizing the operation of thecamera and the lens circuit LEC. The counter CO10 is a hexadecimalnumber system counter of 4 bits for counting the clock pulses CP and thecounter CO15 is a hexadecimal number system counter for counting theclock pulses CPL. The decoders DEll and DE15 are resepectively suppliedwith the respective lower 3 bits CB0, CB1, CB2, CL0, CL1 and CL2 of thecounters CO10 and CO15 so as to output "High" signals at any one of theoutput terminals TB0 through TB7 and TL0 through TL7, respectivelycorresponding to the input data. The Table 9 shows the relationshipbetween the input data and the output data of the decoders DEll andDE15.

The counter CO11 of 3 bits is provided for counting the number of pulsesoutput from the terminal CB3 of the counter CO10. The output terminalsCS0 through CS2 of the counter CO11 and the output terminal CB3 of thecounter CO10 are connected to the decoder DE12, which generates a "High"signal at any one of the terminals S0 through S14 corresponding to thedata of the counter C03 and the data on the terminal CB3. Therelationship between the input data and the output data is shown in theTable 10.

It is noted that the timing Si (i=0, 1,...) means the period duringwhich a "High" signal appears on the terminal Si hereinafter.

A shift register SR10 of 8 bits has its input terminals Ba1, Ba2 and Ba3connected with the three output terminals of the counter CO12 and theother terminals Ba4 through Ba7 and Ba0 are grounded. When the terminalSP of the shift register SR10 is "High", the data on the terminals Ba0through Ba7 are taken in the shift register parallel upon receipt of thepositive-going edge of the clock pulse CP and, when the terminal SP is"Low", the data in the shift register SR10 is output on the outputterminals from the highest bit in a bit-by-bit manner upon receipt ofthe positive-going edge of the clock pulses CL.

AND gates AN31 and AN32 have therein one respective input terminalconnected with the oxcillator OSC to receive the clock pulses CP withthe other input terminal of the AND gate AN31 connected with theterminal TB6. Another input terminal of the AND gate AN32 is connectedwith the terminal TB7 of the decoder DE11. the output terminal of theAND gate AN31 is connected with the set input terminal of a flip-flopFF33 and the output terminal of the AND gate AN32 is connected with thereset input terminal of the flip-flop FF33. The Q output of theflip-flop FF33 is connected with the terminal SP of the shift registerSR10. By that arrangement, the flip-flop FF33 is set by thenegative-going edge of the clock pulse CP generated at the time duringwhich the TB6 of the decoder DEll becomes "High" (the timing is referredto as timing TB6) and is reset by the negative-going edge of the clockpulse CP generated at the timing TB7. The shift register SR10 takes thedata therein as the positive-going edge of the pulse appears on theterminal TB7 and outputs the data in series by the negative-going edgeof the signals of the respective terminals TB0 through TB7.

AND gates AN49 and AN50, a flip-flop FF48 and a shift register SR13 inthe lens circuit LEC are arranged in a similar manner as described abovewith respect to shift register SR10.

In order to operate the shift registers SR10 and SR13 as describedabove, the shift registers are arranged in such a manner that eightflip-flops are provided for each bit for receiving the parallel inputswith the output terminal of each flip-flop connected with the inputterminal of the flip-flop situated at a one bit higher position so thatthe data stored in the respective flip-flops can be transferred to theother flip-flop situated at the one bit higher position. Furthermore,the output of the flip-flop for storing the highest bit is connectedwith the input terminal of an additional flip-flop, i.e., ninthflip-flop, the output terminal of which is used as the output terminalof the shift register. Thus, the ninth flip-flop takes the output of theflip-flop for storing the highest bit in synchronism with the clockpulse, whereby the shift register produces output delayed by one clockpulse.

When the content of the counter CO12 is "001" in the timing TB6 in thestep S0, the content of the counter CO12 is transferred to the shiftregister SR10 by the timing TB7. The data "00000010" of the shiftregister SR10 is transferred to the terminal JB3 of the interface IFthrough the switch SC1 by one bit in series in the respective timingsTB0 through TB7 in the step S1. The data is further transferred to theterminal JL3 of the lens circuit LEC. As the switch SC2 is opened, thedata is input in the shift register SR12 in the order in synchronismwith the negative-going edge of the clock pulses CP. Further, the datastored in the shift register SR12 is transferred to the addressterminals r0 through 46 of the ROM RO through the data selector MP3,whereby the ROM RO outputs the stored data accessed by the address data.

The output terminals La0 through La6 of the shift register SR12 are"0000001" by the negative-going edge of the clock pulse CP by the timingTL6, so that the address "00000001" is accessed to output the checkingdata "11100" from the ROM RO. The checking data is taken in the shiftregister SR13 at the positive-going edge of the signal on the terminalTL7, i.e., at the rising period of the timing TL7. Since the outputterminal CL3 of the counter CO15 becomes "Low", at the respectivetimings TL0 through TL7 in the step S2, each of the data stored in theshift register SR13 is output at the respective rising times of thetimings TL0 through TL7 and the output data is transferred to theterminal JB3 of the interface IF through the switch SC4 and the terminalJL3.

In the step S2 during which the data is transferred to the interface IFfrom the lens circuit LEC, the switch SC2 is OFF by the output CB3 ofthe counter CO10, thereofre the checking data "11100" is taken in ashift register SR11 through the switch SC2 at the positive-going edge ofthe clock pulse CP. The data in the shift register SR11 is transferredto a latch LA at the positive-going edge of the respective output pulsesof the AND gates AN35 in the timing RB6. The data in the latch LA isfurther transferred to a register RG1.

The content of the counter CO12 becomes "010" upon receipt of the outputplse from the AND gate AN33 at the timing of TB6 in the step S2. Then,the data "00000100" is taken in the shift register SR10 at the timingTB7.

In the next step S3, the switch SC1 is ON by the "High" output on theterminal CB3 of the couner CO10 which is applied to the switch SC1thorugh an AND gate AN34. When the output CL3 of the counter CO15becomes "High", this "High" signal is applied to a switch SC3 through anAND gate AN46 so that the switch SC3 conducts to pass the address datafrom the shift register SR10 to the terminal JB3. The address data isfurther transferred to the shift register SR12 through the terminal JL3.The address data in the data selector MP3 is further transferred to theaddress terminals r0 through r6 of the ROM RO, then the datarepresenting the opened aperture value Avo stored in the address"00000010" of the ROM RO is transferred to the shift register SR13.

In the step S4, the output terminal CB3 of the counter CO10 and theterminal CL3 of the counter CO15 become "Low" respectively, whereby theswitches SC2 and SC4 are conductive so that the data "00111" istransferred to the shift register SR11 from the shift register SR13 inthe lens circuit LEC through the terminals JL3 and JB3 and the switchSC2. The data in the shift register SR11 is latched in the latch LA atthe timing TB5. The opened aperture data Avo latched in the latch LA istaken in a shift register RG2 upon receipt of the pulse from an AND gateAN37 at the timing TB6.

In the step S5, the address data "00000110" is transferred to the lenscircuit LEC, whereby the maximum aperture data Avm is taken in aregister RG3 through the interface IF at the timing TB6 in the step S6.In the step S7, the address data "00001000" is transferred to the lenscircuit LEC, whereby the shortest focal length data fw is taken in aregister RG4 through the interface IF at the timing TB6 in the step S8.In the step S9, the address data "00001010." is transferred to the lenscircuit LEC, whereby the longest focal length data ft is taken in aregister RG5 at the timing TB6 in the step S10. In the step S11, theaddress data "0000110" is transferred to the lens circuit LEC, wherebythe longest photographing distance data Dv∞ is taken in a register RG6at the timing TB6 in the step S12. Thus, the transfer of the variousfixed data is completed.

The output terminals La2, La1 and La0 of the shift register S12 are"110" when the clock pulse CPL rises to the "High" level at the timingTB6 in the step S11. While the flip-flop FF35 is set to produce a "High"signal at the Q output (designated FD) thereof when the output of theAND gate AN47 rises to the "High" level at the timing TL7. Also the Qterminal (designated FD.) flip-flop FF35 becomes "Low". Thereforeregardless of the state of the terminal CL3 of the counter CO15, theoutput of an AND gate AN46 becomes "Low" and the output of an OR gateOR35 is "High", so that switch SC3 is made non-conductive with theswitch SC4 made conductive. Accordingly, only the data relating to thelens can be transferred to the camera in the subsequent steps.

In the step S12, the longest photographing distance data Dv∞ istransferred to the CPU 1, the data Dv∞ is stored in a register RG6 bythe output of an AND gate AN41. A flip-flop FF32 is also set by theoutput of the AND gate AN41. Thus, the switch SC1 is made non-conductiveby the "Low" output of the AND gate AN34 and the switch SC2 is madeconductive by the "High" output of the OR gate OR32.

The content of the counter Co16 becomes "01" by counting the pulse fedfrom an AND gate AN48 at the timing TL6 in the step S12. The output ofthe counter Co16 is applied to the input terminal of a data selectorMP3, which transfers the input data to the ROM RO as the address data.The higher 4 bits of the address data correspond to the output of thecounter C016 and the lower 4 bits of the address data correspond to theoutput data of the distance information unit DS. The photographingdiatance data Dv read out from the ROM RO is transferred to the shiftregister SR13 at the timing TL7 and in turn, the photographing distancedata Dv is further transferred to the interface IF in synchronism withthe negative-going edge of the respective clock pulses appearing at thetimings TB0 through TB4 in the step S11. The photographing distance dataDv is taken in the shift register SR11 and latched in the latch LA atthe timing TB5, thereby further being taken in the register RG7 by theoutput of an AND gate AN42 at the timing TB6.

After the longest photographing distance data is transferred to theregister RG6, regardless of the state of the output terminal CB3 of thecounter C010, the output of the AND gate AN34 is "Low", and the outputof the OR gate OR32 is "High", so that the switch SC1 is non-conductiveand the switch SC2 is conductive to allow transfer of only the lensdata.

The content of the counter C016 becomes "10" uppon receipt of the outputpulse of an AND gate AN48 at the timing of TL6 in the step S13. The data"10" is applied to the data selector MP3 to transfer the data to the ROMRO as the address data. The lower 4 bits of the address data representthe focal length output from the focal length information unit FS. Thefocal length data fs is taken in the shift register SR13 at the timingTL7 in the step S13 and further transferred to the interface IF. Thefocal length data fs is taken in the latch LA at the timing TB5 in thestep S14 and further taken in a register RG8. On the other hand, theoutput EN2 of an AND gate AN43 is applied to the set input terminal of aflip-flop FF31, which is set to produce a "High" signal at the Q output.The "High" signal is applied to the input terminal i3, whereby the CPU 1determines that the data transfer of the lens data is completed, causingthe output terminal 06 to be "Low". Then the transistor BT2 (FIG. 4) ismade non-conductive to stop the power supply to the lens circuit LEC.

The data transfer operation between the interface IF and the CPU 1through the data bus DB will be described hereinafer.

If the data on the output terminal OP3 of the CPU 1 is 6_(H), theterminal d0 of the decoder DE10 becomes "High", whereby the checkingdata is read in the CPU 1 from the register RG1 through the dataselector MP1 (FIG. 4) and the data bus DB.

If the data on the output terminal OP3 is 7_(H), the output terminal d1of the decoder DE10 is "High" whereby the aperture data Avo in theregister RG2 is read in the CPU 1 through the data bus DB.

In a similar manner as described above, each of the data Avm, fw, ft, Dvand fs stored in the registers RG3 through RG8 is read in the CPU 1through the data bus DB in order. After the data transfer is completed,the operation shown in the flow chart in FIG. 16 is executed.

It is noted that the circuit arrangement shown in FIG. 17 should bereset by the power ON reset signal PR1, since it must be reset when thebattery BB is mounted in the camera.

Although in the embodiment described above, the aperture value which isnot related to the ambient light level is set by either the aperturevalue corresponding to the focal distance or the set aperture value,other aperture values defined by the maximum light value Ivmax of theflash device, or a further aperture value defined by the maximumphotographing distance Dv and the mean light emission value Iv_(mean)defined by the maximum light emission value Iv_(max) and the minimumlight emission value Iv_(min) can be used.

Additionaly, in the above embodiment, the diaphragm aperture size can bedecreased up to the minimum value if the photographing object is bright,if the interchangeable lens is not provided with the lens data outputcircuit, as the CPU can not detect the flash available range, theminimum aperture value may be limited to a suitable value such as theaperture value F8 to prevent failure of photographing.

                  TABLE 1                                                         ______________________________________                                                  JUDGE CIRCUIT DATA SELECTOR                                         FORCAL    (DJ)          (MP.sub.10)                                           DISTANCE  d.sub.1                                                                             d.sub.2                                                                              d.sub.3                                                                           d.sub.4                                                                            Av   FNO.  Tv  sec.                           ______________________________________                                        30 mm     H     L      L   L    6    8     5   1/30                           31 mm-55 mm                                                                             L     H      L   L    5    5.6   6   1/60                           56 mm-120 mm                                                                            L     L      H   L    4    4     7   1/125                          121 mm    L     L      L   H    3    2.8   8   1/250                          ______________________________________                                    

                  TABLE 2                                                         ______________________________________                                        DATA SELECTOR (MP.sub.1)                                                      SELECTION TERMINAL (SL)                                                                 16                                                                  BINARY    SYSTEM    INPUT                                                     NUMBER    NUMBER    TERMINAL   OUTPUT (DB)                                    ______________________________________                                        0   0     0     0   0.sub.H IP.sub.4 Tvs                                      0   0     0     1   1.sub.H IP.sub.5 Sv                                       0   0     1     0   2.sub.H IP.sub.6 MODE                                     0   0     1     1   3.sub.H IP.sub.2 MEASURED                                                                      VALUE                                                                         (Bv + Sv - Avo)                          0   1     0     0   4.sub.H IP.sub.7 DATA                                     0   1     0     1   5.sub.H IP.sub.3 Avs - Avo                                0   1     1     0   6.sub.H          CHECK DATA                               0   1     1     1   7.sub.H          Avo                                      1   0     0     0   8.sub.H          Avm                                      1   0     0     1   9.sub.H IP.sub.1 fw                                       1   0     1     0   A.sub.H          ft                                       1   0     1     1   B.sub.H          Dv                                       1   1     0     0   C.sub.H          Dv                                       1   1     0     1   D.sub.H          fs                                       ______________________________________                                    

                  TABLE 3                                                         ______________________________________                                        INPUT         OUTPUT                                                          CF.sub.3                                                                           CF.sub.2                                                                             CF.sub.1                                                                             CF.sub.0                                                                           b.sub.0                                                                           b.sub.1                                                                           b.sub.2                                                                           b.sub.3                                                                           b.sub.4                                                                           b.sub.5                                                                             b.sub.7                                                                           b.sub.8                 ______________________________________                                        0    0      0      0    L   L   L   L   L   L   L   L                                                     L                                                                             0 0 0 1 H L L L L L L L L                                                     0 0 1 0 L H L L L L L L L                                                     0 0 1 1 L L H L L L L L L                                                     0 1 0 0 L L L H L L L L L                                                     0 1 0 1 L L L L H L L L L                                                     0 1 1 0 L L L L L H L L L                                                     0 1 1 1 L L L L L L H L L                                                     1 0 0 0 L L L L L L L H L                                                     1 0 0 1 L L L L L L L L H                         ______________________________________                                    

                  TABLE 4                                                         ______________________________________                                        G.sub.3                                                                             G.sub.2   G.sub.1                                                                             G.sub.0                                                                              Ivmax GNO.max                                    ______________________________________                                        0     0         0     1      1     8                                          0     0         1     0      1.5   9.5                                        0     0         1     1      2     11                                         0     1         0     0      2.5   13                                         0     1         0     1      3     16                                         0     1         1     0      3.5   19                                         0     1         1     1      4     22                                         1     0         0     0      4.5   27                                         1     0         0     1      5     32                                         1     0         1     0      5.5   38                                         1     0         1     1      6     45                                         1     1         0     0      6.5   54                                         1     1         0     1      7     64                                         1     1         1     0      7.5   77                                         ______________________________________                                    

                  TABLE 5                                                         ______________________________________                                        F.sub.2   F.sub.1                                                                             F.sub.0     Av   FNO.                                         ______________________________________                                        0         0     1           2    2                                            0         1     0           3    2.8                                          0         1     1           4    4                                            1         0     0           5    5.6                                          1         0     1           6    8                                            1         1     0           7    11                                           ______________________________________                                    

                                      TABLE 6                                     __________________________________________________________________________    DATA      APERTURE                                                                             FOCAL DISTANCE                                                                           DISTANCE                                          d.sub.4                                                                         d.sub.3                                                                         d.sub.2                                                                         d.sub.1                                                                         d.sub.0                                                                         FNo.                                                                             Av  mm         m      Dv                                         __________________________________________________________________________    0 0 0 0 0 1  0   less than 5                                                                              less than 0.25                                                                       less than -4                               0 0 0 0 1 1.2                                                                              0.5  6-10      0.26-0.30                                                                            -3.9--3.5                                  0 0 0 1 0 1.4                                                                              1.0 11-15      0.31-0.35                                                                            -3.4--3.0                                  0 0 0 1 1 1.7                                                                              1.5 16-20      0.37-0.42                                                                            -2.9--2.5                                  0 0 1 0 0 2  2.0 21-25      0.44-0.50                                                                            -2.4--2.0                                  0 0 1 0 1 2.4                                                                              2.5 26-30      0.52-0.59                                                                            -1.9--1.5                                  0 0 1 1 0 2.8                                                                              3.0 31-35      0.62-0.71                                                                            -1.4--1.0                                  0 0 1 1 1 3.4                                                                              3.5 36-40      0.73-0.84                                                                            -0.9--0.5                                  0 1 0 0 0 4  4.0 41-45      0.87-1.0                                                                             -0.4-0.0                                   0 1 0 0 1 4.7                                                                              4.5 46-50      1.0-1.2                                                                              0.1-0.5                                    0 1 0 1 0 5.6                                                                              5.0 51-55      1.2-1.4                                                                              0.6-1.0                                    0 1 0 1 1 6.7                                                                              5.5 56-60      1.5-1.7                                                                              1.1-1.5                                    0 1 1 0 0 8  6.0 61-70      1.7-2.0                                                                              1.6-2.0                                    0 1 1 0 1 9.5                                                                              6.5 71-80      2.1-2.4                                                                              2.1-2.5                                    0 1 1 1 0 11 7.0 81-90      2.5-2.8                                                                              2.6-3.0                                    0 1 1 1 1 13 7.5  91-100    2.9-3.4                                                                              3.1-3.5                                    1 0 0 0 0 16 8.0 101-110    3.5-4.0                                                                              3.6-4.0                                    1 0 0 0 1 19 8.5 111-120    4.1-4.8                                                                              4.1-4.5                                    1 0 0 1 0 22 9.0 121-140    4.9-5.7                                                                              4.6-5.0                                    1 0 0 1 1 27 9.5 141-160    5.9-6.7                                                                              5.1-5.5                                    1 0 1 0 0 32 10.0                                                                              161-180    7.0-8.0                                                                              5.6-6.0                                    1 0 1 0 1 38 10.5                                                                              181-200    8.3-9.5                                                                              6.1-6.5                                    1 0 1 1 0 45 11.0                                                                              201-250     9.8-11.3                                                                            6.6-7.0                                    1 0 1 1 1        251-300    11.7-13.5                                                                            7.1-7.5                                    1 1 0 0 0        301-350    13.9- 16.0                                                                           7.6-8.0                                    1 1 0 0 1        351-400    16.6-19.0                                                                            8.1-8.5                                    1 1 0 1 0        401-500    19.7-23                                                                              8.6-9.0                                    1 1 0 1 1        501-600    23-27  9.1-9.5                                    1 1 1 0 0        601-800    28-32   9.6-10.0                                  1 1 1 0 1         801-1000  33-38  10.1-10.5                                  1 1 1 1 0        more than 1001                                                                           39-45  10.6-11.0                                  1 1 1 1 1        Fixed Focal                                                                              more than 47                                                                         more than 11                               __________________________________________________________________________

                  TABLE 7                                                         ______________________________________                                        ADDRESS DATA        CONTENT OF LENS                                           r.sub.7                                                                           r.sub.6                                                                             r.sub.5                                                                             r.sub.4                                                                           r.sub.3                                                                           r.sub.2                                                                           r.sub.1                                                                           r.sub.0                                                                             DATA                                    ______________________________________                                        0   0     0     0   0   0   0   1       CHECK DATA (11100)                    0   0     0     0   0   0   1   0       RELEASED                                                                      APERTURE Avo                          0   0     0     0   0   0   1   1       MINIMUM APERTURE                                                              Avm                                   0   0     0     0   0   1   0   0       MINIMUM FOCAL                                                                 DISTANCE fw                           0   0     0     0   0   1   0   1       MAXIMUM FOCAL                                                                 DISTANCE ft                           0   0     0     0   0   1   1   0       MAXIMUM ALLOW-                                                                ABLE DISTANCE Dv                       0   0     0     1   0   0   0   0                                                                                    SET DISTANCE Dv                        0  0     0     1   1   1   1   1                                              0   0     1     0   0   0   0   0       SET FOCAL                                                                    DISTANCE                              0   0     1     0   1   1   1   1       fs                                    ______________________________________                                    

                  TABLE 8                                                         ______________________________________                                        DS OUTPUT      m            DATA    Dv                                        ______________________________________                                        0      0     0       0   more than 17                                                                             11001 8.5                                 0      0     0       1   14-16      11000 8.0                                 0      0     1       0   12-13      10111 7.5                                 0      0     1       1   9.6-11     10110 7.0                                 0      1     0       0   8.1-9.5    10101 6.5                                 0      1     0       1   6.8-8      10100 6.0                                 0      1     1       0   5.7-6.7    10011 5.5                                 0      1     1       1   4.8-5.6    10010 5.0                                 1      0     0       0   4.1-4.7    10001 4.5                                 1      0     0       1   3.5-4.0    10000 4.0                                 1      0     1       0   2.9-3.4    01111 3.5                                 1      0     1       1   2.5-2.8    01110 3.0                                 1      1     0       0   2.1-2.4    01101 2.5                                 1      1     0       1   1.8-2.0    01100 2.0                                 1      1     1       0   1.5-1.7    01011 1.5                                 1      1     1       1   less than 1.4                                                                            01010 1.0                                 ______________________________________                                    

                                      TABLE 9                                     __________________________________________________________________________    COUNTER CO.sub.10 (CO.sub.15)                                                             DECODER DE.sub.11 (DE.sub.15)                                     CB.sub.2                                                                          CB.sub.1                                                                          CB.sub.0                                                                          TB.sub.0                                                                          TB.sub.1                                                                          TB.sub.2                                                                          TB.sub.3                                                                          TB.sub.4                                                                          TB.sub.5                                                                          TB.sub.6                                                                          TB.sub.7                              (CL.sub.2)                                                                        (CL.sub.1)                                                                        (CL.sub.0)                                                                        (TL.sub.0)                                                                        (TL.sub.1)                                                                        (TL.sub.2)                                                                        (TL.sub.3)                                                                        (TL.sub.4)                                                                        (TL.sub.5)                                                                        (TL.sub.6)                                                                        (TL.sub.7)                            __________________________________________________________________________    0   0   0   1   0   0   0   0   0   0   0                                     0   0   1   0   1   0   0   0   0   0   0                                     0   1   0   0   0   1   0   0   0   0   0                                     0   1   1   0   0   0   1   0   0   0   0                                     1   0   0   0   0   0   0   1   0   0   0                                     1   0   1   0   0   0   0   0   1   0   0                                     1   1   0   0   0   0   0   0   0   1   0                                     1   1   1   0   0   0   0   0   0   0   1                                     __________________________________________________________________________

                                      TABLE 10                                    __________________________________________________________________________    DECODER DE.sub.12                                                             INPUT       OUTPUT                                                            CB.sub.3                                                                         CS.sub.2                                                                         CS.sub.1                                                                         CS.sub.0                                                                         S.sub.0                                                                         S.sub.1                                                                         S.sub.2                                                                         S.sub.3                                                                         S.sub.4                                                                         S.sub.5                                                                         S.sub.6                                                                         S.sub.7                                                                         S.sub.8                                                                         S.sub.9                                                                         S.sub.10                                                                        S.sub.11                                                                        S.sub.12                                                                        S.sub.13                                                                        S.sub.14                              __________________________________________________________________________    0  0  0  0  1 0 0 0 0 0 0 0 0 0 0 0 0 0 0                                     0  0  0  1  1 0 0 0 0 0 0 0 0 0 0 0 0 0 0                                     0  0  1  0  0 1 0 0 0 0 0 0 0 0 0 0 0 0 0                                     0  0  1  1  0 0 1 0 0 0 0 0 0 0 0 0 0 0 0                                     0  1  0  0  0 0 0 1 0 0 0 0 0 0 0 0 0 0 0                                     0  1  0  1  0 0 0 0 1 0 0 0 0 0 0 0 0 0 0                                     0  1  1  0  0 0 0 0 0 1 0 0 0 0 0 0 0 0 0                                     0  1  1  1  0 0 0 0 0 0 1 0 0 0 0 0 0 0 0                                     1  0  0  0  0 0 0 0 0 0 0 1 0 0 0 0 0 0 0                                     1  0  0  1  0 0 0 0 0 0 0 0 1 0 0 0 0 0 0                                     1  0  1  0  0 0 0 0 0 0 0 0 0 1 0 0 0 0 0                                     1  0  1  1  0 0 0 0 0 0 0 0 0 0 1 0 0 0 0                                     1  1  0  0  0 0 0 0 0 0 0 0 0 0 0 1 0 0 0                                     1  1  0  1  0 0 0 0 0 0 0 0 0 0 0 0 1 0 0                                     1  1  1  0  0 0 0 0 0 0 0 0 0 0 0 0 0 1 0                                     1  1  1  1  0 0 0 0 0 0 0 0 0 0 0 0 0 0 1                                     __________________________________________________________________________

What is claimed is:
 1. A flash light photography system having a camerausing an interchangeable lens in conjunction with a flash light emittingdevice, comprising:input means for serially inputting a plurality ofkinds of data fed from said interchangeable lens including data forcontrolling said flash device; selecting means for selecting the datafor controlling said flash device; and transmitting means fortransmitting serially the data for controlling said flash deviceselected by said selecting means to said flash light emitting device. 2.The system according to claim 1, further comprising:light measuringmeans for measuring brightness of an object to be photographed;calculation means for calculating an aperture value for the flash lightphotography on the basis of the data of the interchangeable lens and thedata of said light measuring means; whereby said transmitting meanstransmits the calculated aperture value to said flash light emittingdevice.
 3. A flash light photography system having a camera using aninterchangeable lens in conjunction with a flash light emitting device,comprising:input means for serially inputting a plurality of kinds ofdata fed from said interchangeable lens including data for controllingsaid flash device; calculating means for calculating the data forcontrolling said flash light emitting device on the basis of the inputdata; and transmitting means for serially transmitting the calculateddata to the flash light emitting device.
 4. The flash light photographysystem according to claim 3, wherein said calculation means contains alight measuring unit for measuring brightness of an object to bephotographed, and a calculating unit for calculating control data forcontrolling said flash light emitting device on the basis of the datainput by said input means and the data obtained by said light measuringunit.